They do have that functionality[0]. The elephant in the room to me when discussing these things is that people aren't wrong when they won't pay for most "content". The overwhelming majority of it brainless filler-noise that a lot of people probably only look at because they don't know what else to do with their time. If actually pressed to come up with how much they'd pay for it, they correctly come up with $0 as the answer. Unfortunately, they don't then figure that it's not worth their attention either.

[0] https://support.google.com/youtube/answer/7636690