Why do…

[|tda| fatal]

Why do rogs /monks / rangers/ intentionally try and get aggro in group content as if they are helping the group so how. Can anyone explain this though process behind this.
If you have a tank in the group and the mob is rooted why are the intentionally getting as close to the mob as possible? Or they are not using evade or FDing at all and rng opening up with flame lick. Am I missing something? How is this helpful in any way? Isn’t it making more work for the healer and wasting more mana which = more downtime for everyone? So just wasting everyone’s time to feel “leet”? I’m confused someone enlighten me pls.