apparently this thread has started a fad. We had a stage like this yesterday but the wsb explicitly stated that you couldn't put any mags in your pouches.
Honestly, I think 'all reloads must come from barrel' has the clear intent of meaning you can't use your pouches (or magnets, for the nascar types), otherwise they would only say that all mags must start on the barrel.
As far as I can tell, the only real effect is to prevent people from using magnets, because with every stage design I've seen except 1 (at an outlaw match), it would only cost you time to put even 1 mag in a pouch.
So if you drop a mag on the ground, you can't use it?