But their position is that people shouldn't be bringing them up because it's 3rd party software, not because bringing up dps is just inherently bad. Harassing people would still be against ToS.
This game's mechanics require coordination. Like it or not, when you're doing group content you aren't really 4/8 individuals who happen to be in the same place. You're 1 group that's comprised of 4/8 pieces, which is an important distinction. There are many times where it's helpful to know what you're group is up to.
As myself and others have said, we don't really need to guess. Parsers have been a thing in many MMOs. Their abuse is pretty rare.