You're saying "players that can't play" will leave. So from the tone of your comment it seems Blizzard should be the one fixing the situation by making content too easy, and chasing away the other part of the population who seek challenging content, instead of "players who can't play" putting some effort in the game they play.
Something that I've wanted to say for a long time, there are guilds with disabled people in them.
Last one I've found was 100% deaf guild with 3/7 Mythic progress in Highmaul. There's a reason voice comm programs are important part of raiding.
There's a guild with 1/7 Mythic progress that has one 100% blind player that's being helped by audio cues and some target-of-target macros etc.
These are guilds with MYTHIC progress!
And then there's people who are whining they can't do Normal, or that LFR is their "end game progress". How someone isn't deeply ashamed to say he, as a fully functioning person, can't do what someone who is more or less heavily impaired, is beyond me.