The "start with communities" is the hard part. You never start with a community, you have to build it. Early adopters define the shape of your community as much as intentional design does. And when you compete with a monolith, who are your first adopters going to be? They'll be people who were kicked off the bigger ship. Most of them were kicked off for a reason.

That's why pretty much every successful social network has a killer feature that everyone is potentially interested in, like Facebook's directories and news feed, or Twitter's microblogging concept, or Reddit's constantly updating Frontpage that'll give you the latest buzz on every topic you care about, or Instagram's photos-as-first-class-citizens concept.

"identical to reddit, but with less censorship of hate speech" just isn't going to make people turn their heads.

There are some communities, line the D&D community that are being disrupted by the end of Google+, they might not be big in absolute numbers, but it’s a prime time to get them as one’s first “real” users.

I think it's interesting that the parent included Mastodon on their list, because it certainly has a very pro- safe space culture, despite it being very tempting alternative to people rejected from centralized Twitter. Mastodon has very strong tools for moderation, and the more "free speech"-aligned instances are quickly blocked from interacting with the main network.