Celebrim
Legend
The math is off there. By that average array, it takes 6 wishes to get two 18's and you then have to multiply by 4 since the party is greater than one. Also, since it's almost definite you aren't 18th level yet and can't cast wish, you have to find all 24 of those wishes.
You interpret this as a problem. I interpret this as a typical Gygaxian way to completely shut down an outcome he finds undesirable. And since I cut my teeth on these rules and had my preferences shaped by them and by DMs who also privileged this point of view, it seems completely reasonable to me to limit wishes in this way. What you find as unnecessary overkill, I find to be completely reasonable overkill. Look at it this way, even if 24 wishes would do the trick, Gygax is strongly pushing the party away from treating Wishes as a valid resource of this sort, rather than something to be used for the process privileged by the rules, namely, to prevent party wipes or recover characters that might otherwise be beyond the reach of lesser magic.