People are idiots.
If you think MMR matched 40% minimum winrate games every game is fair, you’re a fool.
If someone has a bad run and loses 200 SR. How do they get it back? They have to win. However, every game is STILL 40% minimum winrate and still MMR matched even when they’re in elo’s far below where they would normally sit.
Case in point: If a diamond player falls to gold, they have to vs diamond level MMR players to climb …back to diamond and/or the matchmaker will put worse players on their team to “make it fair” 
.
It’s completely uncompetitive and stupid.
They outlined the matchmaker rigs a 40% minimum winrate here:
“Groups and Matchmaking in Overwatch”
I highly doubt many of you will join the cognitive lines together that EVERY game having a 40%-60% algorithmically determined chance of either team winning (as they quickly phrased it in a positive manner) means that, if you fall, it’ll be harder to climb and, inversely, if your SR gets higher than the estimation of your MMR, it’ll actually be harder to lose. Enabling the claims of, “lol I have a million% winrate so your argument is invalid 420 69!” and also similarly demonstrated in countless unranked to GM videos. Nevermind that most of those players can afford to play the game copious amounts but also it’s not often documented how many of them can get stuck in various ranks due to this as it’s embarrassing.
This is why the argument is so divided.
For a game to be actually fair, they should be matched by SR.
If a diamond player falls to plat, they should be placed in plat games which would significantly increase the odds of that team winning possibly over 60% and players would reach their intended ELO in a fraction of the time it takes currently. In the current system that simply would never happen.
It’s facts, the devs have literally told us they both use MMR to match games and the matchmaker is rigging it so neither team has below a 40% chance to lose. It’s fixing matches under the guise of fairness and all it does it stagnate ranks either higher or lower, ultimately, making it so you have to play their precious game more to get back to where you belong.
Edit: It has nothing to do with role btw, OP.