None of these “Apple bad” types read anything beyond the headline.
Nowadays, anything remotely outrageous or negative is very hastily construed to be “Apple bad, duh” without a second thought. We legitimately can’t have genuine, thoughtful criticism of these companies anymore.
Apps can implement their own form of push notifications – most privacy-respecting ones already do. However, it’s an endeavor that’s too much effort for the average dev, so they default to using the existing FCM service instead.