DX11 is not better, it is closed proprietary library/API, officially pushed by company, widely known for Embrace, Extend, Extinguish and other non-ethical tactics, to the standard in computer graphics. As such, many developers actively refuse to utilize it or refuse to use it as the only renderpath.
Some margin of commercial PS plugins actually exist as GIMP versions and are sold for GIMP usage (linux or not).
For the same reason some people/companies prefer to use LibreOffice instead of MSO, on windows(when this OS forced,in 95% of cases, or wanted by individual himself).
I congratulate Victor for getting the contract, although, as in case with opensource driver policy, unless he has skills equal to John Carmack, the raw lack of manpower will make its appearance yet again. But overall, as student or trainee project, this is good for AMD to test his skills. I wonder what will happen if he succeeds... and weather it will happen in windows amd task group.