I think this is one stone I should have left unturned, but let's take a look at some of the problems that the gas-in-mag systems have; expensive magazines, cooldown, extreme frailty of said magazines. These are non-issues with air rig setups. And as for the whole tank argument, it's not 199X (Marui Man lol) and you don't need a fucking scuba tank to play. Besides, most people run with a backpack (HAWG size or bigger) or hydration pack, which would fit a tank big enough for 1500 - 2000 bbs worth. On the flipside, 1500 - 2000 bb's worth of gas-in-mags would cost enough for a whole air rig setup.
And I'm not even going near that comment about the air rig = paintball