I deactivated my first account 8 years ago, but got back on to re-connect with my old pals and acquaintances from back in the day. For that reason, it was fantastic.
After another year, I realized that I can't actually say ANYTHING interesting on this platform without offending someone. There's a lot of variety in my crowd. I have the sense IRL to know that not everything is for everybody, but that doesn't matter much on Facebook unless you want to spend hours and hours hand-crafting subsets of your friends for different topics (I don't). And I have zero interest in posting selfies or status updates of what's going on in my life, so that made the platform exceedingly boring and a waste of time for me. It's a shame, because it does work really well for "connecting" with people (in the shallowest sense of the word).
The people designing Google Groups were clearly on a mission to fix social media. Their bosses had a different mission: to force all Google services into a single account, unified around some "Facebook killer" that was just going to magically work because, y'know, it's Google.
These differing goals came to a head with the "true names" debacle, which Groups never recovered from. But Google did get its One True Account out of it, which is all they really wanted.