You don't think 5+ hour long waits are an accessibility issue? Like I said at the beginning - i am not saying I would involve the ADA, I wouldn't, but waits as long as I've seen shared are an accessibility issue.
The DAS chat window is not like being on hold on the phone where you can put it on speaker and walk away/go about life and it'll be very obvious when someone answers the call. It requires the browser window staying active and it times out if it isn't for a certain time. If you see this and notice it you can refresh (or sometimes I've had to navigate back a page and then come back in) and supposedly you don't lose your place, but if you miss the CM coming in to start your chat, you get disconnected and have to start over. one of the first times I did the online preregistration that happened to me - waited for multiple hours, didn't realize the time out issue, and when I did get back in i had missed the chat and needed to come back and try the next day.
Disney could absolutely make this online process more accessible overall.
ETA: and to be clear, my thoughts on this are irrespective of what accommodation one is waiting for. A 5 hr wait at Disneyland's in person accessibility window would equally be inaccessible and a problem (and that's now where people are being directed to get, for ex, the stroller as a wheelchair tag). The lack of accessibility of a 5+ hr wait, imo, has nothing to do with whatever the accommodation being waited for is.