Right, for offload, but XDP programs also depend on helper definitions, which themselves have not been consistent between versions of the Linux kernel.
I mean, there really is working XDP offload (Netronome, right?) so it can be made to work, but this spec doesn't define the hardest part of interoperability.
It probably still helps to have a standardised baseline. Then the vendors can just document deviations from it, and the deviations are probably quite small, not necessating new compilers for example (just guessing here ;)).
