Apple could degrade it in software. They already degrade DRM'd video playback when it's on a display connection unprotected by HDCP, e.g. when using a VGA dongle.
I've generally been in favor of Apple's hardware changes; for example the original iMac helped the entire industry adopt USB and the Lightning connector is much better than the 30-pin connector (and has a number of advantages over the microUSB pretty much everyone else uses). I've been in favor of their video port changes (except microDVI on the original MacBook Air) even though it created problems for me and my colleagues at work. I'm unhappy about Ethernet being dropped from all their laptop models but it really was an obstacle in their physical design. This change seems unnecessary and I don't like how Lightning is on Apple devices only.
I'm not sure there's an evil DRM plot, I could totally believe Jonny Ive or some designer just didn't like this analog turd messing up the symmetry and digital purity of their designs, especially a connector that's 30+ years old.
The difference in DAC quality is so far below your perception that any perceived difference is placebo.
If you do not believe me, I strongly encourage you to perform a blinded ABX test. I, too, was surprised by the results.