Some of it has to do with app defaults. When you load up YouTube it doesn’t go to the subscriptions, it goes to the Recommended page. It has enough of the new videos from subscribed channels people watch, plus enough of the new videos from channels they commonly watch without a subscription, that people have no reason to go to the Subscriptions page.

Launching from the Subscriptions is an intentional act by people who are actively trying to avoid the Recommendation page, or where the Recommendation page failed to surface what they wanted.

I would not be at all surprised if any using of the Subscriptions page triggered YouTube to adjust their algorithm for that user to see more of what they played on the Recommendation page. They probably see the use of the Subscriptions as a failure of the Recommendation engine.

For a short while my YouTube app on my AppleTV was showing Watch Later and Subscriptions when it launched. I loved it. I assume they were just A/B testing, because it stopped doing that after a while.

I have set my history to be deleted for YouTube after just 3 months. This does surface some videos I have already watched but most recommendations are usually more from my subscriptions