The ISA is much less important than many people seem to think. The RISC vs CISC debate is beyond outdated at this point because no modern architecture actually works strictly like either under the hood. Organizations who did x86 architectures historically had much more emphasis on performance while organizations who did ARM had more emphasis on low power devices. The lingering engineering consequences of that history and the experience of the organizations doing design are orders of magnitude more relevant than the difference in actual ISA.