Man, this takes me back to my first binding class where the teacher had us mix wheat paste so thin it was basically cloudy water and I thought she was nuts. I spent a whole weekend gluing up text blocks that slid around like ice cubes and I couldn't figure out why nothing would hold. Turns out she was right for linings but dead wrong for casing in, and I wasted a lot of good paper before I got that straight. What got me was how much the weather changed things, my paste would act totally different in July versus January and nobody warned me about that. Having two jars going, one thick and one thin, saved my sanity once I stopped trying to make one batch do everything. That guy sounds like he's seen enough bad linings to spot the problem from across the room.

Consider what that hard rule guy is really saying. He is basically saying the win matters more than the people at the table. If nobody comes back next week, he has nobody to play with, so what did he really win? Our shop group does the same as yours and the new folks learn the real rules fast once they feel safe asking dumb questions. Being strict with a first timer usually just teaches them the game is not for them.