So this question is mostly aimed towards the losing part of the game.
Many games out there have very good ranking/ladder systems in place, where a bad day wont ruin your MMR completely.
First games that come to mind are Starcraft 2 and Overwatch, which have different but both very good laddering systems.
Sc2 has a Bonuspool system which helps you on a bad day, if you're losing and gives you a little bonus MMR when you win(I think, been a while since i played).
Overwatch has a different system, I'm not completely familiar with it, but I recall it taking much more of your personal performance in the games into account. So even if you lose, your MMR isnt completely trashed(or that you can even gain MMR).
Valve and Dota 2 has more stats available to the player than any game I've played. They probably hide much info as well behind the scenes.
Which leads me to wonder why there isn't anything of the sort. Right now its; You win 20 and Lose 20, or rather you win X % of your current rank and lose the same amount again. Which means that you can swing on the same MMR until you get lucky with good teammates and winspree.
If i somehow have misunderstood the Dota 2 system, let me know.
Everyone playing the game knows how important each player on the team is. Even if you, yourself perform like 'usual' or very well, you usually cannot carry your entire team.