I see it everywhere on here, and I'm just curious. Is it just a running inside joke between long term members, or is there some kind of legit reason I'm unaware of?
I've never really been a very big Paladin fan UNTIL 5e. I absolutely love the 5e Paladin.
Old-school baggage, I suspect.
In days of old when Paladins were notoriously fussy about the company they would keep (no evils, chaotics only on the very short term) someone sticking a Pally in a party had a lot to say about what anyone else could play; due to these restrictions. This - quite rightly - gave them a bad name.
They have yet to recover.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.