Comment by genxy

I think the issue is then, if you have the same base lineage and you start extending and fixing things, then it will be easy to overlap with new patents that whomever still holds MIPS IP.

RISC-V is mainly a way to avoid IP conflicts, not as a technical breakthrough. MIPS itself was a boring (this is good) implementation of the original RISC papers, but they asserted a bunch of things legally which eventually, along with the legal work of Arm meant that ISAs were effectively owned by their parent corporations.

I'd assert that much like 3rd parties being able to make replacement car parts, that we should be able to make ISA compatible chips. But here we are, RISC-V needs to exist and does, but for legal reasons, not technical ones.

*edit, I forgot to refresh before posting, what bjornnn said.