[Symmetry]

The big advantage that RISC had back when it came out was that you could fit an entire RISC core on a single piece of silicon, something that isn't really applicable in the modern day.

Right now the big advantage of RISC in the high end is ease of parallel decode thanks to instructions always starting on 32 bit boundaries. Which is maybe a 5% power advantage at most. 64-bit x86 has lots of historical baggage and the people doing 64-bit ARM were clever so they're actually about equal in instruction density. It was an advantage to have fewer instructions back in the heyday of RISC but it isn't any longer and both ARM and x86 have tons of different instructions.

When you move down from high power OoO cores to in order ones then having 32 registers instead of 16 becomes more of an advantage and the benefits of simpler decode become more significant too.