buying all the level 1 to level 3 creeps alone and selling them again costs you 3200 (20% of the 16000 total buying cost), that is the price for 3 Supreme Combat Potions (=6750 hp) plus a universal gadget. Getting all the highest level Idols costs another 11000, so you need 14000 spare money to pull it off. That means you can only do this trick when you are a very high level. I tried this trick ages ago and it didn't work at all (even in the version where minions where really strong) , the more creeps you have the more deadly AoE effects get and you can't resummon them. It could confuse new players, that is the only reason why it could be necessary to remove it but that is it.
right i just went to do further testing on this, and i found u can buy the monks, summon them sell the totem, then buy the archers. summon them and then sell the totem, then buy the minotaur, and then sell that, and if u have the magical coin purse favor item u get more money for selling them back then it cost to buy in the first place, so u can go get urself a full army, sell the totem and then buy a HP / DMG item before you even start the game, totally broken imho
just tested myself again, with the purse you still only get 80% of your invested money back so you lose 405 money for getting 2 archer, minos and priests which you can't resummon, at the start of the game. You also lose quite a bit time at the start of the game as it takes a while to buy->summon priests->sell->buy->summon archer->sell->buy->summon minions->sell->buy armor. (took me more than 15 seconds that means your enemies get all flags in the beginning)
Again it could confuse new players (they might even think you cheat) but it really isn't that much of a practical strategy - although buying monks and selling the item and then be careful to keep them alive might be useful but that would be far from being a broken strat. Sure they could change it that way that your minions die when you sell the idol, wouldn't mind that, but it is a very low priority bug in my opinion.