20 years ago they launched Google Reader to do exactly that. ~10 years ago they killed that, too.
But I wish generally they would stop hoovering up and monetizing my personal data. F'ckers.
Google and Facebook make most of its money off ads because the reality is that users don't like paying for stuff directly.
And to be fair, I don't regret it, because I have another consideration -- I can easily get some nice Xiaomi phone and root it and install various blockers and alternative YouTube frontends... BUT... my Google account is very valuable, a lot is tied to it and Google has become a bit trigger-happy banning and deleting accounts. So I am not willing to risk it. Hence I paid up.
They might use your viewing history to target ads in other places. And they definitely use aggregate/anonymized viewing patterns to suggest similar videos people might like, but I don't see an issue with that.