Serious question - what rules in 5e encourage bad player behaviour?

Not one person ever: “There is no song about Oath of Devotion Paladins”

… this list contains like 3 items phrased differently ~7 times each.

“This person had a family/friends” “This person was supporting someone else” “This person liked their pets”

repeat …

5 level 3+ characters vs 3 CR 1 bugbears and a handful of CR 1/4 goblins.

That is a trivial encounter. Of course you wrecked them.

You like the way she goosesteps huh?

Counter argument - she’s a space nazi, and nazis are for punching.