Where did they move?
They might move to different Mastodon instances (via the built-in migration system) or find a new network, but they are not getting killed with no way to find each other afterwards.
At the same time, based on my own personal experience, it is absolutely impossible to get people to move to another platform or service even for the purpose of discussing future plans.
My exceedingly strong advice is to have multiple points of presence defined as a matter of course, one of which should be a simple email list (which provides persistent contact information), regardless of any awareness of an impending platform shutdown.
I agree it is difficult in the situation you describe, which is not mastodon.technology's situation.
I'd created both a subreddit (https://old.reddit.com/r/plexodus) and wiki (https://social.antefriguserat.de/index.php/Main_Page) to memorialise at least some of that discussion, as well as the on-platform discussion.
That last is of course now unobtainable, though there were over 700 snapshots of the community homepage saved to the Internet Archive's Wayback Machine, see:
<https://web.archive.org/web/20190401071102/https://plus.goog...>
Because of the mechanics of both G+ and IAWBM, actually navigating to articles from that archive ... mostly does not work.
The G+ community had over 4,000 members (pretty good for late-stage G+). The subreddit ... a hair over 300.
People. Will. Not. Go. Off. Platform. Even. If. That. Completely. Fucks. Them. Over.
It's a really perverse dynamic.
vomits in my mouth a bit
Regarding spam, there is some (seemingly inevitable in any community involving humans). But frankly Mastodon, right from the beginning, focused heavily on Moderation tools. Figuratively speaking, no expense has been spared to make it easy and convenient to block bad actors (or instances) from your account (or your whole instance).
With USENET people expected to see every posts in the newsgroups they were subscribed to, and a lot of people would complain loudly if anything was missing. With a network like this nobody expects to read everything. At the same time receiving everything is easier (still) - if you federate with a couple major endpoints you get most stuff. There will be challenges with this as the network grows but I spent too much time ensuring we got messages from newsgroup X within Y hours (less was unfeasible, as there were still sites exchanging on a schedule via dialup).
With respect to spam, once you accept you're not likely to see everything, things get a lot simpler and you can apply a lot more aggressive filtering.
Personally I'm working on my own ActivityPub implementation, and one of the things I've used on Twitter in the past very effectively via the Twitter API was a simple Bayesian network used to rank things to surface interesting stuff, but lots of room to apply more sophisticated machine learning there too.
Maybe there could be a variant of NNTP which allowed some amount of advertisement posts in between. Then let the maintainers keep the proceeds from those?
Facebook and Twitter are extremely popular services, and have been at or near the top of their categories for over a decade.
Google+ was an attempt to challenge them, shut down after it failed without ever becoming anywhere near as popular.
That is the number of Google accounts that didn’t go through the effort of disconnecting from / opting out of Google+. For a few years, all new accounts were automatically enrolled in Google+. It’s likely an extremely inflated number compared to the number of users that engaged with Google+ social features.
Citation: https://arstechnica.com/gadgets/2012/01/google-doubles-plus-...
It's probably a better example of a service that never got off the ground.
Twitter and FB could survive for decades just on the their current cash positions alone.
One of the challenges of a social network, especially in a declining phase, is that there is far less commercial value being generated at the same time that various sorts of costs, including attacks on the network in both technical and social/economic senses increase. High-value members abandon the network, and those who remain are either stuck (say, because of institutional circumstances elsewhere), or are actively seeking to exploit other members.
This means that Trust & Safety costs are constantly increasing at the same time that recruiting talent to serve that role becomes increasingly difficult.
What the true cost curve looks like isn't clear, but basing your statement on a constant cost based on present experience is ... probably flawed.
This is especially true at Facebook's scale.
Despite (and in contrast to) the absolute massive marketing effort that Google put into Google+ right from launch, it never achieved mainstream success as anything other than an OAuth login tool. That doesn't mean nobody used it, but it was always niche.
It's not a proper comparison for Twitter or Facebook, which grew organically and are both mainstream successes as social networks.
It was the best social network that existed, and before it shut down it had so gotten so much right that I think no others have matched anywhere near the complete feature sets.
Having the biggest social network sucking up personal data to feed the ad network is the reality we are in. Having Google with a larger collection of personal data linking everything to a large social network would have made things worse. Google+ forced real names which made facebook force real names. Google appstore and preinstalled apps you cannot remove force location data. Google obtaining your social graph leads down a dark path.
Still, technically, Google+ was far ahead of their competition.
Their email about shuttering went into a tab in Gmail and didn't spot it, a suddenly my entire YouTube channel was deleted.
Hundreds of hours of work of crafting early videos of Elite: Dangerous and the beauty of its simulated galaxy just gone.
Luckily backed up on a NAS but I've never put them back up.
<https://old.reddit.com/r/dredmorbius/comments/1sxfar/reddit_...>
That said, Google's stated communications regarding Google+ had and have been questionable from the start. I'd had my own part in this in addressing the true size of the active community on the site, which was far below the 3--4 billion listed profiles and many hundreds of millions of active users touted. In practice, probably closer to 4--6 million true frequently actives within 30 days or so (itself not unsubstantial), and perhaps 100 million who'd been active at some point.
<https://ello.co/dredmorbius/post/naya9wqdemiovuvwvoyquq>
But I'd take that stated reason with a large dose of salt.
It began as a venture by a couple of graphic artists, focused on artists. It happened to have (for a few iterations) a quite clean design based on Markdown, and (with a couple of what should have been reasonably small tweaks) could have done well in the long-form text+images space (now largely owned / failed by old-school blogging engines such as Wordpress, Medium, and Substack).
The features it had, including Markdown's sections and tables was why I'd posted that particular take on G+ there. It simply presented the information better than any other readily-available platform I was using at the time.
In 2015 a bunch of trans activists and sex performers who'd been hounded off Facebook by its Real Names policy wound up on Ello, and a few people arrived from other platforms (I was at the time a refugee from G+). For about six to twelve months it was the New Hawtness, and attempted a few pivots to the space, but performed fairly poorly in doing so. My own Ello profile has a link to a set of curated posts, one section of which details various gripes and failings.
One thing Ello did do was organise as a B-Corp with a community focus. That went swimmingly until it didn't, with the first accepting VC money then being sold to a collector of such sites. The B-Corp language seems to have disappeared, along with the community principles texts. What's left is now ... a sort of vaguely art-aggregation site with an interesting history but little future so far as I can tell. It's burned virtually all its early adoptors (myself included).