It's enough to make a stronger hive so it doesn't get robbed, am I right?
@Pokitren sorry i can't post in that section. seeing as you asked me a direct question i'll reply here.
hives are naturally strong enough to defend.
so its not that you make a hive stronger but rather you don't let it become weak.
hives become weak because of issues like mites, poor mite treatments, diseases, swarmed badly and hasn't recovered in time, or mistakes by the beekeeper.
in robbing season the hive should be fairly strong, as the hive will still decline as it goes into winter.
i've got some pics somewhere of large amounts of wasps at one site and we never had issues with wasps robbing hives. hives will defend.
the other thing you will most certainly hear about is people blame robbing for their hive failure, which is not true (most of the time).
the hive died from other causes which the beek cannot find/understand or is simply ignoring.
don't be those guys.