I've never used the app but I'm sure they also request location information and a lot of people agree, so I can make a reasonable guess for most people where their home location and corresponding voting districts are.

Also, over time, the type of media delivered may subtly shift anyways. When I started using Facebook, it required a .edu domain to register and focused on listing your courses, finding peers in your courses, campus events, and so forth. Now, it looks absolutely nothing like that, yet I still have a Facebook account (which I rarely check but thats another story, many of my peers appear to still actively use it). For now it's a bunch of silly videos, maybe it won't always be that way.

You may be lured into a platform, grow accustomed to it and the convenience of a user base, then slowly go along for the ride as the platform shifts direction. Perhaps you may be vigilant of this (the reason I stopped using Facebook many years ago), however, a large portion of people may not.

Now, whoever manages TikTok has a direct route of information to a wide group of people providing they don't upset them or a competitor doesn't lure them away.