Yesterday on a DXB-MCT-DOH ticket the WY agent said the UAE authorities required proof of flying out of DOH before I could check in baggage through to DOH and get my boarding passes. I had to fire up my computer at check in, and retrieve my ticket (DOH-elsewhere). The agent took my e-ticket number and entered it into the check-in system and there it was.The boarding pass and baggage were allowed for the DXB-MCT-DOH flight.
Otherwise I would have been "stuck" in the UAE with no way to fly out to DOH....
That said, entering the UAE and leaving (at passport control was easy enough..