Most of the problems you are experiencing do exist. They’re just not matchmaker problems.
They’re people problems and there are exactly zero changes or improvements to the matchmaker that can solve them within the game design of Overwatch.
For instance, your issues with ranking individuals in a team game. You’d need to make it not a team game to solve this problem.
Your issues with skills being widely variant on teams. People not only have and value different sets of skills, but people also have good days and bad days, and sometimes your team just syncs better as you happen to have similar ideas of how to play. There’s nothing that a solo-queue, automatic matchmaker can fix.
But, and this is important, the tools are there to not have this happen, so if you’re experiencing this it’s quite specifically you’re own fault for not using the tools available.
Your issues of GM level players being stuck in Bronze? That’s obviously BS. It’s not a problem. Will a Gold player win a few games in Platinum? Sure. If you watched your own video, you’d know that would be expected to happen about 25% of the time. I wouldn’t be all that surprised if a Bronzer played in GM and won a game or even two, they’re only 1/12 of the outcome.
GM level players not instantly being brought up to GM from Bronze, well, they could increase PBSR but that has residual effects that have been shown that people don’t like.
The issue of too wide a variance on teams? They could increase the queue time but again, it’s a tradeoff that people don’t like.
There are others I mentioned above, too.
Are you seeing a pattern here? It’s not that all the complaints that are false, it’s the proposed solutions that make zero sense at all, blaming the wrong thing, or if the solutions do actually make sense, they cause more problems than they solve.
ETA: I’ll even go so far as to say that I can imagine that there are certain playstyle/character combinations that will fit well in a broad range of tiers, so that the same person could actually fit well in Diamond or Gold. If this were to happen, it wouldn’t be a problem with the matchmaker, it would be a problem with game design that makes a character’s skill floor and ceiling too close together and thus impossible to measure with accuracy. Could also be someone who can’t learn to be effective in a lower level but has the mechanics that will suffice in a higher level and happened upon the right strategy. Again, not a MM problem, it’s a combination design/player problem.
Measuring physical data is really, really hard. And this data is moving around.