Apple didn't design the PowerPC or make custom variances. Motorola and IBM did it. Especially Altivec was added by Motorola, and IBM didn't like to add it to their PowerPC CPUs when Apple asked for help, when Motorola had the 500 MHz glitch bug back in the day.
There is a nice coverage on this topic at https://www.youtube.com/watch?v=Tld91M_bcEI (Why the Original Apple Silicon Failed)