[chongli]

The equation is the same one as for software: why did Google use the Linux kernel instead of developing their own kernel for Android? Because Linux is available and free to use; duplicating the effort of Linux would not have been worth it at all.

The RISC-V architecture is superior to all of the major commercial architectures out there. It's also free to use and has a significant amount of headroom for private extension. So what's stopping a company like Apple from using it for their next phone? They already have the necessary human resources to design an SoC. The main barrier is software recompilation. Well, the RISC-V target is specifically designed to be easy to recompile to: it's not in any way a radical departure from the common ideas out there.