You are greatly misunderstanding group content. It's more than just a healer taking on the extra load of a bad player. The entire group must take on that load. Every high end content has hard enrage timers that, if they aren't met, will instantly wipe the group. If the entire group can't take on that load, then the run is a failure and ramming your head into a wall multiple times won't change that, thus, a change of party is required. If they can, most players are going to resent that obviously weak link who got carried or, worse yet, can jeopardize future runs. I'm not saying everyone needs to bring top percentile dps numbers, but I am saying there's generally a reasonable expectation that people know how to play their job and handle/learn mechanics so that they're not a hinderance to the run.
You are basically saying, "If you can't carry bad players, you're not a good player," and that's not fair to people who don't want to put in so much work for someone else's sake. Do you know what happens when you tell people that's what you need to do if you don't get properly compensated for that? That breeds resentment and anger in the group. People will probably quit of their own volition because they held a reasonable expectation that people could pull their own weight. You are encouraging "DPS has no culpability" which 100% makes bitter players, if not just healers.