Don’t know about your particular problem, but I’m pretty sure it was largely a response to iPads being sent to mobile sites with horrible usability thanks to navigator.userAgent.match(/iPhone|iPad|iPod/) or the server-side equivalent. The problem was amplified by the release of the 12.9’’ iPad Pro, so self-identifying as a Mac made sense.
Well I’m glad Apple prioritizes us over you the. I don’t care that you want it a different way. Apple forcing the end of bad practices in this instance is a win.