Anything in roleplaying is possible, why not this stuff then?
Exactly, say it's a curse, or magic in nature. Or maybe just One of Those Things that we don't know how to change, but the character does their best, and kind people around that character support them and help them be as able as possible.
Then let people make characters without disabilities if they want (which is already the case). But what if someone wants to play a character, or see characters, that face similar challenges to the ones they do? And then get to play them overcoming those challenges!
This is not exactly equivalent, and I'm not asserting that you meant this, but imagine in a different time someone saying, "I don't understand why anyone would want to play a non-white race, since it just opens them up to racism, when they could just fit in and be normal." I consider that to be along the same class of argument as the one we're discussing here.
why would a person want to fantasize about having a disability
To imagine a world where they are the same, but their disability is not an impediment. A more perfect world, rather than imagining themselves as other than they are.
Yeah but this is a game for characters who are played by people who exist in a world where that is not the case, so maybe a little sensitivity is called for.
At least make it hard for them. Keep squeezing, and they may move on to some easier racket. Do nothing and you guarantee they keep robbing from you in broad daylight.
Expect better, agitate for it. Get excited for a livable future. Write letters and make phone calls. Go to a protest. Resolving to do even one of these in a year puts among the rarefied few who actually put in the extra 10% effort to move progress incrementally forward.
book of nature wut wut grandeur written all around us etc