Isn't any policy in the airline industry always a mystery?

I've been on about 100 legs with QR the past 12 months, most of them between DOH and RUH but I've been to DXB, LHR, BRU, MLE and KWI as well. I always travel Y class, and always travel with only carry-on baggage. I have one regular size bag which usually weighs in at around 7kg (not that anyone ever checks) and one rather big laptop backpack which adds another 6kg or thereabout. I have never had any issues with bringing them both on board, regardless of what the policy says.

But YMMV.