I think it's pretty simple why people like Vaush and that sort of cohort.
Y'know how there's those boomers who have news blaring on the TV or, less frequently, talkback radio blaring in the background 24/7?
I think that's what streamerbros are to the younger generation.
It's something that you can put on in the background while you're playing an FPS game which doesn't really require any particular mental engagement because there isn't really anything particularly difficult to grapple with and very little that challenges the dominant worldview or which considers hegemony in a different light.
It's mostly just a regurgitation of the prevailing narrative and prevailing tropes and the occasional gotcha-style "dunking" on someone.
I don't play FPS games because it's not to my taste. There's a small handful of RTS and turn-based RPGs that I'll play which I know like the back of my hand and at times I'll listen to podcasts or lectures or audiobooks on theory/history/current affairs from a radical perspective and while I'm playing those games even then, with games where I know exactly how I'm going to play, what's coming next, dialogue that I can skip over because I don't need the in-game direction to advance the plot etc. I still find that I can't focus sufficiently if the content gets too heavy.
His content is vapid but I think that's a feature and not a bug, at least to his audience.
He also reaffirms people's biases so you aren't encouraged to do any introspection or self-reflection or hard personal work.
He assuages the latent guilty conscience of a non-reader by reassuring them that they always have the correct position and their assumptions about the world and theory are correct. He is contemptuous towards reading theory so, for the non-theory gang, this makes them feel better about themselves and it even makes them feel elevated above the people who read.
Vaush skim-reads Wikipedia on stream and delivers hot takes on matters that he is obvious to. The person this attracts is the type of person who also skim reads Wikipedia for a small fact that "vindicates" their position in an online debate.
He has a degree in sociology and I remember on a stream clip he discussed Durkheim's concept of anomie as being, like, nihilism and whatever. This is sociology 101 stuff and anomie has nothing to do with nihilism but he couldn't even provide a basic definition of this simple sociological concept. Tbh, Durkheim's not my jam and I can only ever remember 3 of the 4 categories in his quadrant discussion anomie on the spot because I'm cursed but there's no shame in not knowing this stuff if you're schooled in sociology but all it takes is to pull up an image of the quadrant and to discuss anomie in relation to its opposite in order to elucidate the concept. (Legit came across a suspected Vaushite on social media use the term anomie in a way that implied the same meaning as Vaush did and which in no way applied the correct meaning one time and I called them out for getting their definitions from Vaush rather than bothering to spend 5 minutes reading up on it in Wikipedia before using the term and they never replied lol.)
Same can be said for how he had to look up Cypress to discover that it's a country before discussing "Sigh-pree-yachts" as if he knew anything about the subject. This is the go-to guy for a cohort of people who want to form their opinions on geopolitics smh.
It's just trash. It's junk food for the mind and that's its whole appeal.