I think it's just simply better at it. As users, we provide signals to these systems in the form of engagement metrics. But these systems have to interpret those metrics. If I'm highly engaged with a piece of content, the system has to figure out what characteristic of that content appealed to me. I feel like YouTube in particular uses way too coarse/siloed characteristics that results in funneling into a few characteristics. But with TikTok, I get the sense that it ends up with a much finer grain idea of what I like.

Another major source of tuning is going to be the frequency and the novelty of content injected into the stream. TikTok will throw new things at you more frequently than other platforms. Because viewing a Tok is so low investment and easy to swipe past, they can afford a few misses and still keep you in the app. This leads to a better search process for the things you care about.