x86-64 isn't more "standard" than ARM, and RISC-V systems aren't necessarily open.
x86-64 chips typically have architecture manuals that the general public can access, for one. That's one sense of a standard, however incomplete.
Documentation is not the same as a standard...
When the same code can run on multiple chips from different vendors, how to write that code becomes a standard, regardless of how you obtained the knowledge. Documentation may not be the standard itself, but it sets one.
Cool. Then you go do that. In the meantime why crap on others?