I do sports pistol shooting as a hobby. Recommendations have improved recently, but before you never were never further than two clicks away from ISSF championship chronicles to videos by disturbed people with firearms.
There was undeniable steep gradient towards extremism, how it worked on me in particular is irrelevant. It is a numbers game.
The propaganda by totalitarian states is an entirely different beasts, it reaches into all walks of life.
I'm more worried about the censorship leading to totalitarian states than extremist YouTube channels.