I heard people say the same stuff about Apple slowing down performance on iOS. People complained about it for months and years, and Apple fans and “Geniuses” gaslighted everybody by saying they were just imagining it, until we found out that Apple was actually doing it. The reason they did it was not bad, but the lack of transparency was.
We also saw the same thing with the keyboards. People complained about the terrible reliability and how it was overall just worse for years, and not until later, esp when Casey Johnston I believe documented her keyboard experience, people kept telling others it was a matter of preference and anecdote != data, to the point that Apple, after 3 revisions, basically went back to the earlier design.
The anti-Apple sentiment can be tiring, but a lot of it is driven by the rabid pro Apple sentiment that assumes nothing Apple does can be wrong.
Specifically, even if x86 is not more open than ARM, if you believe that Apples implementation of ARM would be more open than what they have right now, then you are clearly relying on faith that is not backed up by any evidence at all. Apple for the past decade or so has been on a steady and consistent path of locking things down on both iOS and MacOS and they will proudly tell you about it as well.
Again, I don’t even entirely disagree with their locking things down (I’ve seen how much more comfortable novices can be with iOS than MacOS, although, at the same time, I’ve seen the same novices grow with MacOS in terms of stuff they can do in ways I haven’t with iOS), but that doesn’t change the fact that it is entirely reasonable to assume that if Apple changes from 3rd party processors to in house ones they will likely lock things down further.