I strongly agree. Lack of support for Plexamp is a dealbreaker for me. At minimum they're going to need to support Spotify or they'll kill the product. I think it will probably need YouTube support as well. There is a worryingly sparse amount of information published about what it will support.
Yep. I'm afraid they're going to "require" that you use Apple Music and HomePods to be useful. I'm pretty interested in trying the product, but that depends on Sonos and Spotify support at minimum.
Well, plexamp is a dealbreaker for Apple that more and more wants you to buy Apple Music and all their services. They have more to lose by opening to plexamp users, who are not the more prone to spend money, or other services, than to lock users in their very own walled garden. Open source software on consumer friendly hardware is the way now.
I don't know if that's obviously true. I'm sure Plexamp is small potatoes compared to how many are on Apple Music, and there's a solid chance that anyone running a Plex server is doing it on a Mac.