From a tanks perspective:
“Healers are always dead, its support diff”
From a supports perspective:
“Their DPS keep killing us, while our DPS haven’t killed anybody, its a DPS diff”
From a DPS perspective:
“Our tanks make 0 space for us, refuse to shield us and don’t peel for supports, its tank diff”
I honestly don’t pay those people any mind. They’re just looking for someone to blame oftentimes when they’re underperforming.
“It’s everyone else’s fault, but mines! Don’t yah know? I’m an Overwatch gawd!”
This never happened when flexxing was a thing.
“Dude u suck at tank let me rein”
role queue really did cause more problems than it solved
Even worse when someone uses it as a compliment 
I remember more games where there was no tank or maybe just one road hog.
Open queue was better, a team came together and adapted or they lost.
It is a stupid, vapid thing to say. There is something worse though, making a thread to complain about it.
Wasn’t my experience, I found open que incredibly frustrating. I had left the game and role Que was the change that brought me back. Doesn’t mean there aren’t still issues to solve but going back is not the answer imo.
Neither system is perfect. Far FAR from it but open queue was better. But now it’s basically “not real comp” in my eyes because of role queue.
RQ split the playerbase even more and ruined queue times.
Opinion diff
if anything, open queue allowed dps players to avoid RQ.
So uh, no.
Ping diff
This is just something people say to make themselves feel better.
It’s the same thing as someone saying “GG” after a lopsided match ends.
I feel like supports are lucky when it comes to “XX diff” because your teammates usually only notice your healing. So as long as you’re healing them and they can tell, it’s less likely for your team to be toxic about your performance. On a relatednote, it’s also not that easy for your team to tell your contribution besides healing as well. Whenever I’m doing well, my teammates often times tells me “good heals” even when I’m on zen or lucio 
Tank and especially DPS players are more susceptible to being judged for their performance though.
There are some ways tell though. If you get just steamrolled and the match takes 2 minutes, it’s probably a tanking issue. But also, players are toxic and will say “GGEZ” on 1 to 1, 99%/99% over time, and get a nano’d bob at the end. I normally assume someone who says “X Diff” and is that class/character, that they don’t win so often, so they try and latch onto anything they can.
I say it because it makes people mad
If its my team tilting on each other i start trash talking our ana, which is me. Then they start defending our ana, once again not realizing its me. Shows the general awareness of the people who say this.
When someone types diff the game should autoload the replay and force them to watch from every teammates perspective before they can re q 
And then some games the enemy team has two flanker dps and a Lucio and a Winston all over you in the back line , provide no assistance or peels and blame you for them not getting heals when they lose to the other two players on their team. Supports get blamed too in dumb ways but yeah it is less often.
You know what’s dumber than that? Making a post complaining about what other people type in a chat that can be easily muted.
Team averages FTW!