I think when you add "why try to reinvent the wheel?" to the end, it is less of a question and more of a statement. Similar to saying, "Why would you do that?" after someone does something silly. You aren't actually asking them why they'd do the thing. You're saying they ought not have.

But they didn't say that?

They did, but they've since edited the comment.

That is exactly what they said.

The rest of the reply seems to be an answer (as far as you can get with Apple)

I don't think it's wild speculation to say Apple is looking for efficiencies they may not have been able to get with GPUs especially performance-per-watt since so many of their devices are mobile focused

To be fair to nsxwolf, I did not originally explain. I tend to gradually expand my comments. The first iteration was just lashing out at this trend I see on this site which I highly disapprove of: facile reactions to any work that the commenter does not understand. I really detest this reaction that boils down to, "I once heard about a tensor, so clearly I have a better idea of whether this chip should be invented than the experts working at Apple."

Basically just look up Google's TPUs and the reasoning behind them.