Both of those were a vendor X electing to stop updating framework A in favor of framework B. That’s a high cost for vendor X’s users, but if their business depends on vendor X, they have no choice. Maybe they can switch to vendor Y at that point, but now you are switching both vendors and frameworks.

Replacing CUDA with another framework has much lower motivation. That advantages of the new framework must cover the switching costs and the risk of such a switch. All while CUDA continues to evolve and allow access to additional features.

Apple and Microsoft had something of a captive userbase. New vendor on the block trying to replace CUDA does not.