Many people follow specific channels and only look at content from them, not random bullshit teenager videos that show up in the random/new/trending pages. If you only look at these contents, then yes, you're going to get those bullshit annoying videos.

It's the same with Reddit, Lemmy, and others, people follow the specific channels they want and avoid the trending/random/new stuff.

For an example, I follow Digital Foundry channel for their detailed analysis/reviews, The SciShow, Sorted Foods, and so on. I click my subscriptions on youtube and it only shows these high quality content for me. Our family spend hours on these contents. They're not available anywhere else.