Because people want to use their fancy new hardware to play games? Linux market share wouldnt be increasing so fast if Valve didn’t do the work so why shouldn’t Apple do the same?
They don't really block games though. It's more like they don't want to maintain the roads the games need to run on.
Transitioning to ARM wasn't possible if they had to support 2 x86 ABI's and an extra ARM 32 bits ABI. Throw in another migration and you have an untestable number of legacy combinations.
