TheSword
Legend
I don’t think it’s a problem imposing limitations on players. There several spells I outright ban from the game (leomunds tiny hut/rope trick) and I’m fond of restrictions on character building where it suits the flavor of the campaign.So I'm partly just playing devil's advocate here, but the OP did mention wanting to discourage players from playing wizards. Does that make it okay?
To answer my own question, the problem is probably that it's a case of trying to solve an out-of-character problem with an in-character penalty. Which rarely, if ever, works.
If the intent is to create a harsh restriction to discourage players of wizards then that doesn’t stop it being harsh. The OP asked for an opinion, not our permission. I personally don’t see why you would want to discourage wizards though. Who cares whether a player chooses sorcerer, wizard or warlock.