Bedrockgames
I post in the voice of Christopher Walken
Obviously, always assuming the worst can be annoying and can get in the way of discussion....like always assuming a player would introduce a fictional element only for a mechanical advantage and not for any other reason.
I am not assuming the worst about this. There are honest differences in preference on this matter. But know the group your in. And in certain groups, claiming your uncle would give you that kind of information, might be perceived as cheating (unless there was a very good reason for it to be the case in the campaign). Again, I don't even share Maxperson's preference here. I just think people are betraying an unwillingness to even engage his playstyle. He isn't asking anyone to eat nails. He is saying at his table, you shouldn't act on things your character wouldn't know, and he includes among those things like monster vulnerabilities. That is not a difficult lane to stay inside at all.