I have a friend who had a 4 year old Mac laptop. He was big into recording his own music with ProTools. When he got a new iPhone 6, iTunes wouldn't work with it. He was instructed to upgrade Mac O/S, which did get his iTunes working but then broke ProTools. 4 years of recording work was lost unless he purchased a new ProTools license.
So what you're really complaining about here is a 3rd-party software package (ProTools) not working on a recent operating system release? How exactly is that Apple's fault?
For years Apple was seen as the platform of choice for graphics artists and musicians. They really were the core constituency for a very long time. ProTools is the music industry standard for music production and editing. When you buy ProTools on Apple, you're buying the whole platform and should reasonably expect it to be sustainable over the useful life of the hardware. To ask who is responsible here is a very good question.
From where I sit, I look at Apple and the apps you get for it as a platform. If the software vendor isn't keeping their product current through at least a 5 year life cycle, where does that responsibility lie? What kind of support does Apple provide to its vendors? This is one of those things where you'd love to be a fly on the wall, listening in to certain conversations. It's never a simple this guy or that guy dropped the ball.
I love being able to take my CD collection and rip it to a free, open source standard, like flac. And then being able to play that back on my hi-end system and not have to worry if it will be compatible when I upgrade my gear or music software 5 or 10 years from now. I love that I'm not tied into a commercial service like iTunes, or any of the others (Spotify, Tidal, etc). For me music is something best heard played by live musicians, or failing that, on a great system in my home. I've always felt that there's too much snake oil in consumer technology - overpriced cables, music services, gear and proprietary standards.
I just like being more hands-on, with open standards, whether it's audio or computing.