One of the big selling points of x86 is backwards compatibility. If you have some OS from 1990 you can still run it (without emulation or virtualization, so long as it doesn't depend on clock speed), which is pretty crazy.
Slight aside, there are a lot of reasons that Itanium failed, but certainly one of them was lack of backwards compatibility.
Slight aside, there are a lot of reasons that Itanium failed, but certainly one of them was lack of backwards compatibility.