People who have no idea what they're talking about and can't reconcile the fact that they've just grown past the game. So instead of it just being a normal function of basic human development, they talk about how shit the game is. And the way you can find this out is by listening to them talk about Vanilla servers. 99% of the time it's about some nostalgic point.
Because if you take an objective look at Vanilla today, it's shit by comparison to basically every MMO on the market right now.