No idea if it has or has not.
Assume for a moment that there Are people that have spent $500+ to amass a collection of legendary troops. If they had it hasn’t had too big of an impact on the game or we would hear a LOT of complaints about them.
Conversely, if it hasn’t happened, then adding a less cost effective way to acquire legendary troops is not likely to make it happen. If someone was already willing to shell out big bucks, they would have done so.
Either way it reinforces the notion we shouldn’t be afraid that the ability to unlock troops for gems would induce a rash of “credit card warriors” unbalancing the game.
