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

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

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.

NGL I keep reading posts and wanting to try pf2e. But then I read the rules and realise the system is garbage.

I love the only meaningful challenges being within a 2 CR range of the party. No really I do. the restricted pool of creatures to build from is just great.