I would argue that it’s the nature of having a mature and complex product. Adding new stuff is hard because you have a lot of legacy code / UX that you have to accommodate for. You need to move slower because it’s easier to break stuff in a more mature product.

I’d also argue that Apple and Google’s research teams are generally hearing the similar stuff out of their end users, so it’s to be expected that both companies are going to prioritize similar functionality.

That was my experience when I’ve worked on massive products. The complexity of the product impacts development speed, and shared understandings of user desires results in similar feature sets between competitors.