All the other content recommendation systems force you into a ghetto and are highly auto-regressive. They only show you content like they already showed you, so you will never be exposed to new things. This hampers discovery, and you end up with only a few winner-take-all accounts with mass appeal and mass distribution (e.g., "Mr. Beast") who are broadly not interesting or specialized.

TikTok is more stochastic and is more likely to give wider circulation to niche and esoteric subjects. Booktok could never happen on YouTube shorts or Instagram.

Using those other platforms is like shouting into the wind. You could have videos up for years and not get 50 views. With TikTok, a random video could be seen by 250k people.

A corollary to other systems being so auto-regressive is that they are much more dangerous for vulnerable people. If Instagram decides to start showing you extremist or otherwise political content, that is all you will see. This is the "rabbit hole" effect that people have commented upon. This doesn't happen to the same degree with TikTok; while this content can be recommended, it's not all that will be recommended.