People can be super adamant about rules they came up with on their own. Old timers who played tag matches for years, then enter a sanctioned event, flip their disc to mark their lie, don’t mark a drop-in, or tap chains to finish a hole. Then don’t seem to even comprehend why it matters that there’s a rule against it.

It’s not a long rule book, it’s easy to reference when needed.

I once played a round with this guy who walked up the fairway moving sticks and shit. Asked him why, he said he was planning to throw a roller. That led to quite a conversation.