TL;DR Tbh I think most people just stayed on reddit or are here.
Totally gave up reddit in favour of kbin/lemmy and discuit. I'm quite happy using both at the moment as they serve different purposes: kbin gives access to a lot more content, especially memes and news related so I'm 99% of the time a lurker here.
Discuit is still a very small community and favours more discussion based content, but since they just added image post support that will probably change. There's only 4k or so accounts and a lot of people who migrated from Squabblr due to the main admin's attitude or something. It's mostly a pretty relaxed place with a few rocky moments and the admins are nice, anyone harassing other users gets dealt with pretty quick as it's still small.
Ah thank you so much for linking that, every time I see that evolution of dance video come up it reminds me of the kollaboration one and I kept forgetting the name for years.