The point that people such as BelArgUSA and others always fail to address is HOW do you go about identifying the "best stick and brains" in order to promote them?
The amount of @rse!ickin and cronyism that goes on in those airlines that use "merit" promotions has to be seen to be believed.
Who do you think an average airline manager is going to promote, given the chance? The F/O who once refused a flight on fatigue grounds or who carried extra fuel into LHR (as advised by the UK CAA) or the guy who never refused to do anything asked of him, no matter what the professional implications?
BelArgUSA says his new airline gave him his "self respect" back (bit worrying that he seems to define himself by the number of stripes on his sleeve!) by making him a direct entry captain, but I bet it didn't do much for the self respect or morale of the F/Os at that airline, and I bet he wouldn't have gone along with that idea during his time in Pan Am!
If you REALLY want to see some poor pilots promoted, then just go down the management selection route!
To paraphrase, seniority is the worst system for promoting F/Os .............................. apart from all the others!