Sadly, my experience with large, poorly-run conventions makes me think that a lot of policies are all about "Hey, we KNOW the convention is an absolute mess of overcrowding, long lines, and lining up for 3 hours in a non-air-conditioned hallway to cosplay, but we're not going to do anything about it, therefore we must all suffer together, so what makes you so special that you don't have to suffer along with the rest of us?"

Or, if they are afraid that people are going to pretend to have disabilities in order to get a better con experience, well, it's a lousy part of a long, long history of labeling people as malingerers, but also... it's a signal that maybe they should try to give everyone a decent con experience.

(My bitterness, I will show you it. Until I came to WisCon I thought it was totally normal for every event to start hours late.)