I used Duty Finder for a Level 50 Dungeon PUG as a Scholar. I had a tank that started getting pissed at me because I "wasn't healing". Nobody was dying and in fact, nobody's health dipped below 40% at any time. He started complaining that he wasn't being healed.
Not being healed?! EOS was busy overhealing like crazy. Essentially, he wanted to be topped off at all times. I did casually notice (but didn't say it out loud) that once my DPS started being higher than his, the complaints magically appeared. But this is not the first time that a tank suddenly got pissy if their DPS was poor. And I have also seen other party members become toxic & bitchy if they didn't have full HP bars, even though they were in no danger of death.
In the last dungeon I did as a Healer, I started doing completely unnecessary AOE group heals & shields as PR. Then I knew I was done.If I have to overheal & play poorly to stop players from harassing me, that is the opposite of fun.
Toxicity is different from advice. I welcome helpful tips during an instance! "You should stand to the left side of the boss" or "It helps if you pop that steroid at the beginning of the pull so we can do more DPS" is genuinely helpful. I appreciate that.
On the other hand, "You need to heal!" and "Healer, do your job!" is not helpful. It creates a negative atmosphere & encourages total silence in an instance, even when communication would help.
So I switched to DPS and what a difference! I am having a lot of fun! Nobody compliments me (other than 1 group where a girl said that I was hot) but nobody bothers me either. I am never the target of toxicity. In return, I am constantly super-nice to the tank and healer because I remember what it was like to be in their position.
Disclaimer: None of this applies if you have a static. In that case, you are probably enjoying healing & tanking and that is a good thing!