Apple being an off and on competitor in the space was always strange.
They failed to commit, and often let their tools languish, despite the following. Odd.
It's even weirder cause some of it was self-inflicted from making Macs very unfriendly to GPUs in various ways.
Apple moved into the space when Adobe's willingness to support the Mac faltered during the transition from classic MacOS to OSX.
Once Adobe finally committed to supporting the new platform, it wasn't as necessary anymore.