And personally, I'm not even sure it crosses that bar.

RISC-V somehow manages to be more fragmented than x86 (which is impressive), and just can't compete on instruction density.

I think a large part of the issue with RISC-V is that it predates (public knowledge of) ARMv8 by a year or two, so it couldn't use it as inspiration. If you compare RISC-V to 32-bit ARM, the comparisons are much more favourable.