I know this is an extreme idea, but maybe you're not supposed to climb any ranks? Maybe your current rank is exactly where you belong? Sometimes someone on your team brings you down, but it's statistically just as likely that someone is bringing the enemy team down. The only variable in that equation is how good you are. If you're not gaining ranks, maybe that's where you belong?
There are so many people in this thread complaining about playing in bad teams and not gaining ranks who don't even consider the fact that the rank distribution for almost everyone right now seems to be between 30 and 70 because people haven't played enough to gain/lose more ranks. With that in mind, most people are supposed to be around 50 rank. That's what Master Overwatch shows as well: the ranks have a gaussian distribution with 50 being the most common rank. I know everyone thinks they are good at this game, but most people will stay between 40 and 60 no matter what. Most people are not supposed to climb any higher (disregarding over a longer period of time as they improve obviously).
That's not extreme, if the ranking is supposed to indicate skill, your skill doesn't change too much in like a week or month so you shouldn't really level up or down too much from the point you start. It's true.
The system works well for example in case of surefour, he's the highest ranked player in the game right now, he started a brand new account, played his placements, went 8-2, ended up at 78. Almost same rank he got on his main playing with c9 stack. System is working properly here recognizing the best player, those statistical noise and variance won't affect him very much as his inputs put him at the far end of the bell curve either way.
Now as you say, most players are in 40-60 range, but there is still a huge difference in basic game understanding and general awareness and macro. These people might not be that far off in general micro and shooting hence dropping in same ranks but in this game, picks and team composition counts for a lot as there are hard counters for about anything or how you coordinate your ult for example, so in any level if this guy that picks some hero that's readily countered by the enemy team for example, it doesn't matter too much how good his aim is, his aim is as good as the other team's dps probably since the ranking he got playing his dps, or might lack awareness of hero synergies and waste his ults again and again, good ults are game winning in this game and it's all about timing. One weak link can drag every one down and add to that, there are many other outside game and outside of your control issues that can lose you ranks now. So I'm not really sure if the system is right for the busy middle to give a good experience overall, maybe more things should be considered. I don't know, what I know is that it feels awful playing with people that are easily blown up by a bastion again and again instead of trying to find a solution. It feels they are times too generous with the ranks they've assigned or too harsh.
Overall, I think the system works very well on high end of the curve, but like how bad you have be to get to 20 or something? It appears that almost no one is getting there, maybe they need to be more diverse here, maybe a normal distribution doesn't represent that good of a gaming experience, not everything is statistics and they have to change the formula somewhat in the middle of the curve that they've lumped most players in, I don't know what's the solution but in other games like starcraft2, the ranking curve is somewhat skewed, most are not ranked in the middle for example. in the end it's a game and you want people to feel good too by playing and progressing, not everything has to be hard reality that you suck and stuck at 48 forever.
M and TF2 player, but most people here probably got their introduction to him because of Overwatch.