For the non European pilots applying and asking about the MCC (Multi Crew Cooperation) certificate.
It's pretty simple.
For European operators operating multi-pilot aircraft (part 25 aircraft) you have to have either an ATPL or a CPL ME IR with all ATPL exams passed AND an MCC certificate. It does not matter how many hours you have on multi-pilot aircraft. The MCC certificate is a pre-requisite for employment. Whats the reason? In order to be issued a JAA/EASA ATPL you have to present a valid MCC certificate. That's why once you have an ATPL you no longer have to present it to an employer. It's already been presented to the licensing authority.
Now, Qatar and the GCC in general follow the European licensing system very closely; reason, many were previously British territories and they inherited their aviation regulations from the British and have continued to follow very closely after this and through the JAR and now EASA changeover.
So unless you have an ATPL an MCC certificate is required (because that's the way they roll as regards licensing and operating on a part 25 aircraft).
You could talk to the QCAA about it, but that's the same as going to any Aviation Authority within Europe and telling them they are wrong.
They aren't. You need an MCC certificate. They're not that expensive so go grab one at your nearest approved MCC training provider.
Good luck and may we all find paradise, health and wealth in the desert.