You have your Instagram, then your close friends list on Instagram. Then your finsta. And the close friends list on your finsta.
All of these are just g+ circles.
The advantage of FB was also that you saw content, whereas on Google+ everyone would have it locked up and you couldn't see it, great for the less popular types.
Parts of it made sense, maybe a bit too early, not enough people using it.
Circles feature was also marketed the wrong way. The G+ ad showed a lady bad-mouthing her boss in a circle that doesn't include him. Who's gonna put that much faith in the separation? The entire point of a finsta is that it's not a supported feature, so you can believe that it's totally separate and also has a different name. You'd use the finsta to bad-mouth your boss or perhaps even less wholesome things.
Also I think Messenger may have been faster than Hangouts. It was not faster than GChat, but it didn't matter because Google killed it and that definitely drove me to use Messenger more.
https://techcrunch.com/2014/04/24/vic-gundotra-the-father-of...
(It also helps to find target communities not well-served by incumbents -- like, perhaps, the multiple communities who interacted poorly with Facebook's "real names" policy. But instead, Google leadership insisted on copying that policy, and in a particularly heavy-handed way, to the point that Google employees couldn't register accounts with nicknames that they were actually known by to colleagues and family alike; see e.g. https://www.firstpost.com/tech/news-analysis/why-googles-rea... )
Google+ was pretty great. It had some really wonderful special interest communities, and it was really easy to separate my family identity from my tinkerer identity from my friends stuff. The whole circles and squares thing was a wonderful, front and center, privacy-focused metaphor, like some product people actually listened to what actual online community Ph.Ds were saying.
But the execs made everything worse repeatedly in an attempt to drive success metrics up.
"We already have a huge user base, we'll just automatically sign them up for <new thing> and get it off to a running start". No, these users will hate you for it and in fact ruin the experience for the select few who are actually interested. Meanwhile executives will tout the rosy user growth metrics, declare the launch a success and collect their bonuses.
There is no substitute for old-fashioned organic growth. Start small. Focus on early power users and listen to their feedback. Have something unique that sets you apart from the competition and attracts more users. This is how Instagram, Snapchat, TikTok and the like were able to establish themselves in Facebook's presence while Google+ failed.
Adding a new notification about everytime someone follows you is just asking for people to avoid the product
Poor UX management
Google+ was competing head on with Facebook which had a huge leverage in terms of the network effect.
Well, it was more colorful I suppose.
It wasn't just the execution, the basic idea was bad. The few people this overly complicated thing would appeal to are probably not the kind to use social media either.
Instead they forced it on everyone using any Google product, hurting the product itself, but also preventing the critical feedback loop that would have allowed G+ to improve, and become organically successful.