Radio and newspapers(including internet articles here in general) are a one way street. With Tiktok, you not only get access to the users device via the app, but it is also a two way street. Tiktok gets to choose what it feeds you.
And what you describe is also true in a lot of countries(I can choose my medium). However, with newspapers, radio and television what you feed the population is readily visible to anyone. I can turn on the telly to see what is being streamed. This is not the case with an app. Unless the government watches you 24/7 and I doubt that. The costs are prohibitive. The thing that does exist is metadata. If I were to visit terrorist.com or bombmanual.org.uk I would make a list. But watching TikTok all that is being seen is me communicating with content-servers(here the subject that needs to be watched also changes from the user(me) to the proprietor(the company)) from them and protocolling the content of everything watched, unless you break encryption at scale, and monitor everyone is also prohibitive. Not to mention analysis of the content. So Tiktok is the perfect vehicle for subversion of a foreign nation if I want to play for time.