As a user that notices the impact of this data: please no, thanks though.
Have you ever visited youtube's home page in incognito mode? It's... bad. Really bad. Not allowing any company to use this (obviously very private) information in ranking would simply make their products suck, horribly, compared to today.
Do you like the personalized recommendations because of channel subscriptions?
I always get the "anonymous default" home page with YouTube and don't care. The home page is just a wasted load before I can start typing in the search bar. As a bonus, staying incognito means all the videos on the right-side panel are related to the current video. Not related to a music video I have playing in another tab.