One fighter to deack the town, one Lanc formation to WF the town, and an M3 with troops racing in as soon as the bombers flash the base. Fifty players resupping in M3s cannot stop that take because none of them will get there before the troops. One decent fighter pilot, or two mediocre ones, can. Resupping is not more effective than defending.
Where resupp *is* highly effective is when the attackers WF multiple towns, leave, and try to sneak one of them while no one's paying attention. Resupping the town means you don't have to babysit it, sitting by the map room in a GV doing absolutely nothing for the next hour or two (depending on how porked the strats are). Sneaking bases like that is a legitimate tactic, but foiling the sneak by resupping is just as legit.