Wouldn't a blank homepage be exactly what you expect if you had no tracking enabled? The algorithm that generates the homepage is probably totally stunted with only empty logs to draw on.
You could make a list of demographic fitted choices based on info on the user.
One wonders if you couldn't whip up something that would whip up a list of choices by operating locally only on the users history returning just a list of things to show on the page and forgetting it when the user closed the tab.
Most users won't understand how that works. As far as they're concerned "youtube watches what I do", and any explanations about how the algorithm runs locally but google can still see what you watch if they look at IP logs will be far beyond a typical users desire to understand.
Honestly having occasionally glimpsed the logged out YouTube page which appears to do this... I'm glad that I don't have to deal with that either.
As for what they should do, I think populating the homepage from the subscriptions list (either literally as an ordered list or by some algorithmic "watch time vs average watch time for this creator", I don't care) would be preferable.
If the goal were anything but discouraging disabling watch history, they’d take care to design a page not so strikingly barren.
Video categories, subscriptions, trending searches (not saying we’d WANT that), Google-curated selections, recommendations based on user choices (“what kinds of videos should we show you, want daily news/sportballs/music recs?”)
