Apple did not just “get ARM to add something” they got dozens if not hundreds of engineers to think really hard about how to roll out MTE with no performance impact on all their critical attack surface in a way that actually targets specific exploit strategies rather than just going “oh ok our allocator has tags now”. Google (and Android) took a very different approach. Of course it’s very possible Apple messed up and their implementation is not as secure as it was designed to be but they did put significant effort in many areas that I feel are novel.