I was just watching a video on this yesterday: https://www.youtube.com/watch?v=5McB6-2r-ds

Apple’s implementation of MTE is relatively limited in scope compared to GrapheneOS (and even stock Android with advanced security enabled) as it’s hardware intensive and degrades performance. I imagine once things get fast enough we could see synchronous MTE enabled everywhere.

It is curious at the moment though that enabling something like Lockdown Mode doesn’t force MTE everywhere, which imo it should. I think the people who are willing to accept the compromises of enabling that would likely also be willing to tolerate the app crashes, worse performance etc that would come with globally enabled MTE.