Placement on the ladder/skill isn't necessarily correlated to having a good opinion on what is healthy or unhealthy for the metagame.

All you need for a decent placement on the ladder is to take a good team from someone else, play the team till you understand it, to be able to determine your and your opponents wincons from team preview and info gathered throughout the game, to be able to identify and play lines that lead to your wincon, understand and apply risk/reward properly, and to be able to read (and condition) opponents to a degree.

You don't actually have to know anything about game balance or health/unhealth of a metagame to reach, say, top500 elo in any generation (I haven't been top100 so I won't speak for players better than myself). You can just be fundamentally solid and play the gen enough to have a decent guess at what your opponent's sets is from preview and whats revealed from his play/info he shows. You just need to know what your opponent has, not whether its good or not.

While there is some obvious overlap between understanding the metagame on a more intricate and holistic level and general pokemon skill, having the latter does not guarantee the former and vice versa. Just because someone is dogshit at the game doesn't mean they aren't entitled to an opinion about how fun a meta is to play or how strong a pokemon is. They might just be bad at everything else.