The toxicity is getting crazy... here's some psychology for you. Be better, win more.

So I just want to address the culture trends I'm seeing already THRIVING in this game (might actually be already worse than OW), and give people some real understanding of human behavior to ACTUALLY help you win more games, rather than throw them by yelling at your teammates. To preface, I'm saying this as an actual expert in human behavior, it's my career to collect and report behavioral data to Fortune 100 companies (including AAA devs):

The main point:

Team comp and raw player skill mean almost nothing without the player's willingness to collaborate and make a serious effort in the game:
Reducing these things for a teammate is the most effective way possible to force a loss. The slang "tilt" is exactly this, and it's a real thing, with a scientific basis of proven causes that people choose to ignore.

Sub-points:

Stop picking someone on your team to blame:
Attempting to punish (blame, command, trash talk) a person, rather than constructive help or polite requests, immediately will reduce effort and willingness to cooperate for the vast majority of people. That's not an opinion, it's a scientific fact supported by decades of research. If you want teammates to perform, there is absolutely nothing more helpful than positive reinforcement (collaboratively strategizing with them, humor, praising when they actually do something helpful).

Stop commanding teammates to swap and yelling at them when they don't:
A polite request? Absolutely, but accept a no, and adjust. Roles are open for a reason, hero selection exists for a reason, and people choosing to stay on a hero or role they aren't performing well on is perfectly valid. Does it suck sometimes? Sure, but maybe they are trying to get better at fighting against countering comps, or trying to become the best at a specific character. Instead of having a meltdown and yelling at them (which will do what is talked about above), adapt to your new knowledge that they aren't going to swap if you are someone who can and will flex, or find ways to play better together with them (and both get better as a result). Another point to this is that playing a less than ideal comp with people on characters they know well will almost always be a heck of a lot better forcing people onto heros they don't play.

Don't trash talk the other team, either:
While sure, it's not harming your current team, this just feeds the growth of this kind of toxicity overall. Culture is learned, and being toxic to anyone just increases the frequency of it happening to you.

Don't be a hypocrite:
Everyone has bad games. When blaming someone on your team you may be pretending you've never had a bad game in your life, but everyone knows for a fact that isn't true. Everyone experiences the toxicity directed at them at some point, and choosing to participate in it will only increase how much it happens to you within the community. This also applies to the idea that "if my team doesn't swap or do what I say, they aren't playing for the team." Know who else this applies to? You. What can YOU do to help the team, given your knowledge of what the rest of your team is playing and how they are performing? You would be amazed at how often swallowing your ego will help you win games. Is someone feeding? Try pushing with them or pocketing them. DPS failing to get kills? Try to play with them and help secure them. Heals can't keep up? Try playing in a way to take less damage and reduce healing load. I'm not saying these are full-proof, but it's a hell of a lot more effective than turning the lobby into a shouting match.

If nothing else, remember that this game is brand new:
People are still learning, and everyone learns differently and at different rates. Just because you've been playing 12 hours a day nonstop, doesn't mean everyone else is in the same boat. From a personal perspective: I climbed to Plat 1 in 2 days playing one character, and get flamed regularly for not being able to full flex at that level with twelve hours in the game. Relax, and try not to turn this game into a new toxicity meme already.

I frankly challenge everyone to test this for themselves. If you are someone who regularly yells at your teammates: play a set of games, use comms, and make everything you say collaborative or constructive (that does NOT include commanding people to do things they don't want to). I can almost guarantee you are going to climb higher than you are right now.