TikTok "ForYou" algorithm is very very impressive in its recommendations. 2 people might have very different experiences with TikTok. So if you start using with some regularity, even if you don't press like in anything it will figure out what you like and what you don't. I am very curious about how it measures content engagement.

View length. If I watch a whole video then that's positive signal between me and that video (no matter if I actually like the content or not). Netflix gets that as well. I can say I like history documentaries, but Netflix knows I really use their service to watch trashy reality TV shows in the middle of the night - and then they use that information to choose what sort of shows to produce.