How many other airlines out there will provide those wonderkinds with the left hand seat of a 777 or A330/340 at only 6500-7000 hours? Yeah, not many. You can expect to wait a lot longer for a left hand seat of a heavy jet nearly everywhere else.
Right or wrong, that type of career progression is extremely rare. Plus, who wants to be left hand seat of LCC and do so many sectors per day, every day for the rest of your career? It would be like that movie Groundhog Day. I can see why so many Ryanair and Easy refugees are looking to flee. Some people might prefer multi-sectors to long haul - whatever floats your boat.