It's not just that either.
I feel that the harassment towards people under-performing in parties is currently disproportionately nasty towards tank and healer contribution rather than the DPS. And I imagine part of it is because of the view that many see DPS as expendable for various reasons not even related to parsing at all. At the same time, the tanks and healers perpetuating it themselves are likely also doing it precisely because the community is now reaching a point where there's mutual distrust among public parties, and they cannot counter underperforming toxic DPS shifting the blame around without outright admitting that they're parsing themselves.
Being able to see tank and healer contribution towards a fight is very easy. But for DPS, it is ridiculously hard, and accountability is difficult to gauge. People go by enmity meters, but the problem with that is that most top-tier DPS will keep it as low as possible, because not only will they probably want to give the tank some room to switch out of tank stance and into DPS mode safely without worrying about the well being of their teammates, it's also because they know they will do so much damage that they will freaking die if they don't mitigate their enmity properly. And nothing tanks DPS faster than death.