I think the difference in experience I have between twitter/fedi and cohost/tumblr (because those two sets are pretty similar to me) is that on twitter and fedi I see posts by my friends and mutuals with their thoughts and feelings or we're all having conversations, but on cohost and tumblr it is mostly a few posts here and there but primarily curated content of other people. Instagram is somewhere in between bc people tend to share a lot of their own stuff with a little bit of reshares or DMs of good posts.
And... I like hearing about what my friends are up to, what cool experiences they've had and their feelings and thoughts on various stuff, but I don't care as much about randomsteve2024's memes. Not that they aren't good memes, but most of the funny memes someone is sending me over instant messanger or discord already.