Isn't it funny how one man's feature is another man's bug?
Not supporting logging in with a Google account to keep subscriptions and history synchronized across devices is exactly what disqualifies it from consideration for me, and I suspect I'm not alone here.
For those like me there's YouTube Vanced, which is almost an exact clone of YouTube except without the ads, allows you to disable a bunch of distracting "features" like info cards and watermarks, and with the ability to use MicroG in place of Play Services for the actual logging in with Google feature: https://vanced.app/
Isn't it great that we both have the ability to choose the YouTube replacement app that works best for us despite Google technically "owning" the platform though? This is why I love Android. (EDIT: Re-read this and realized this could be seen as inflammatory. Really did not mean to start a platform war. Just glad that Android is a choice that's available to those who value this kind of thing.)