I think the parent cared more about it being driven by a specific company’s interests than Apple’s in particular, because this makes it somewhat difficult to use on other platforms. And I’d argue that Apple’s engineering talent, while good, is not “the best”.

Hard to say if it's the best, but likely the worst attitude of the management on top when it comes to collaboration and general progress (which languages should enable).

Oh def. Apple has been too slow and/or conservative about opensource.

Off course, that's why they keep having security issue after security issue (macOS root exploit to iPhone issue reported by project zero).