No I cannot agree to that. At qatar and other places,arabic is not at all a must to join flying.
Crew from non arabic speaking countries are recruited as language speakers and for the purpose of arabic language,there are crew recruited from arabic speaking countries.
On every flight there is atleast one arabic speaker and there have been occations where aircrafts took off with none of them,even on regional arabic sectors.
With regards to ground staff,the same system applies. however if you know arabic,ofcourse it carries more weight!