Clearly, you are not playing with randoms or you ar in the top 1% of players.
I was not saying that they need to get -M+ rating because it does not even make sense, the way rating for M+ works.
And nobody needs to carry anyone, but if you decided to join a group and you are ok with the group than you should stick to it. It could be that you can leave after 10 deaths without any penalties, or after a vote to end the dungeon or something.
Some people are super toxic can leave after the tiniest error and they mess up your key even tho it would have been timed.
There should be a system in place to incentivize players to stay and finish the key.
It's funny to me that people that don't have issues with leavers are against it, probably because they are the elitists that leave groups and mess up people's keys
)