I actually wouldn't mind seeing a professional team rock up with two 190-195cm locks if they were the best possible players (especially if they had two 190cm-ish back rowers with them).
Show me footage of a lock losing a lineout because he's 5cm shorter and I'd be very surprised. You usually lose due to bad execution of the throw/lift, poor movement/footwork on the ground, or bad timing. Outside of lineouts, other than a few rare circumstances like lock-on-lock kick off receptions, losing that height is not big deal.
The moment you broaden the physique you're looking for there's more talent to pick from, creating a john-west situation.
I mean for fuck's sake, Maro Itoje is considered the greatest thing since sliced bread and he's only 195cm.