Linux doesn't run on VAXes. Furthermore, Linux supports those who break ix86 compatibility with their fancy new chipsets. It neither supports the old standard or enforces the new one.
Nobody is obliged to let history chain them in place; if you think you can do better then POSIX, you have the right to try and it's sad that you'll have to endure abuse to do so. Everyone benefits from the work that came before them; *nix systems have been harvesting features from Windows and Apple for years, and designing systems that don't work on those OSes, with no apology.