I think all of this is really important. I often get irritated when someone isn't performing how I would like them to, and rarely stop to think that maybe there's a reason they can't help. Not because they're a parent who's not watching their screaming kids, or playing while drunk, etc., but because sometimes there are physical limitations that can cause problems. That doesn't mean they should be yelled at or kicked. I've seen some people die to the same mechanics over and over, and there might be a valid reason why, but people rarely ask them if they need help (you'd think a mentor would, but nope).
It's important to remember that this is a game. Games are meant to be fun, but that doesn't mean we have to step all over other people so we can have fun at their expense. Remember that the person on the other side is in fact a real living person, and there's no need to treat them as any less. Disabled or not.
