To me, I watch YouTube when I have some time to do so and make the active decision to open the app… then let me know about which of my subscriptions have recent videos. I just can’t imagine being in the middle of something else and dropping everything because someone posted a video. But different people are different I guess.
Another factor is that videos are not permanent. If you don't watch a video immediately the creator may take it down or private it.
Time sensitive stuff I… kinda get. But I would get stressed out if that was actually the norm. I really don’t like the idea of “engage now or you’ll miss out” in my entertainment.
I can't imagine wanting YouTube to be able to push content onto my phone at arbitrary times of its choosing. What benefit does that give you over the subscription feed and home screen?