What a shame. What's the point even? I'm not going subscribe to YouTube premium anyway, and even less install and use the YouTube app. What happens with this move is just that I will just use YouTube less. I believe that's the case for most people who chose to use YouTube in a browser precisely for background playback. As an example: knowing that I won't be able to keep the sound playing for the 5 minutes in between…
Perhaps that's what they desire. Serving YouTube video has marginal cost and you provide marginal zero value. Losing you as a customer is probably desired.
That's a very narrow view. YouTube is the only reason I have a Google account. Because of it I use some of their other products. And because I'm connected to my YouTube/Google account, they can track my behavior across products and across devices. My usage profile has value if only because it can be correlated to others (who don't bock ads), and because I share link to their platform on social media and messaging app. That's still true even if I'm able from time to time to continue listening to a YouTube video while my phone is in my pocket. But I will share less link and leave them a lot less usage data if they push me away from their products.