You open with, "This is patently false," but then don't really seem to contract what the OP said.
Nomikais are both. If anything it's just an excuse to drink, and each company or team would decide how they drank. It starts in college with bukatsu nomikais. And there are good ones, and the ones where the ring leader is arrested for serial rape. That happened at Todai, and is definitely not normal, but unless you're the leader (there is always a leader) how are you to know until you show up and everyone starts drinking? Much like frat recruiting in the States. My year, someone died (1997 I think it was).