Two main things about this game's battle content:

1. There's group-level DPS checks. DPS checks aren't always the responsibility of a lone individual.
2. Most battle content involve either 4-man, 8-man, or 24-man - ie. everyone has to work as a team. Everyone works in the team, based on the role they queued for.

It's one thing to be calling out people for self-perceived low DPS, but sometimes you run into people who pull REALLY low numbers (ie. Warrior pulling more DPS than MNK for example). It really isn't the responsibility of the rest of the group to suddenly up their game to account for the lack of ability from this one player. While you may argue about protecting the fun of said player, what about protecting the fun of the 7 other players who are trying to clear said content?

I don't have an issue as long as we meet the group DPS checks, but if we are not able to, I wouldn't be able to tell who could further improve. The fact that there's DPS checks almost everywhere, but no way to actually measure DPS, outside the use of certain tools which I will not talk about, is a bit of an irony.