you have to build bombers to carry paratroopers and you only carry one of them and that can only be dropped 2 spaces away from friendly forces. The bomber commitment alone precludes the issue of “flying shock armies from buck rogers”. Unfortunately some feel that you should be able to build and use them w/o bombers and i know 100% that this is a broken game, however, the OOB is somewhat balanced.
but if you feel its not balanced you can impose a “training cost” of 1 or more IPC every time you drop airborne, paid to model training of these elite specialists. Also, limit the build of one airborne per turn ( example: if you build 3 bombers in a turn you only can use 1 additional airborne drop the turn following placement and 1 each following turn for the next 3 turns)
This would preclude the really stupid and impossible idea of Germany building lots of bombers and thinking they will have an immediate Sealion because they didn’t buy anything for 5 turns and all of a sudden spurged on bombers as some kind of trick.