I'll throw myself into this conversation. No pity party here, just providing an example. I'm in a seemingly odd spot that needed the former DAS program for queues, no longer qualify for it, and cannot reliably use a mobility device at the current advice of Cast. I have three separate rheumatological diseases that affect a lot of things, with the bottom line being my knees, back, and sense of balance may work perfectly normally, get kinda out of whack, or completely crap out. Any combination of the three affected areas could act up at any point, or just one; there's no way to tell.
Using a wheelchair gets very painful quickly due to pressure on my back (prolonged touch = pressure in this case), but it does save my knees and occasionally my sense of balance. Walking around the park is an unknown, but it provides the best odds of things staying on the positive side since I can compensate mild to moderate mobility problems a bit. I've taken 30+ trips, so I have a very strong sense of what does and does not work for me. Standing in the typical stand-by queue is miserable. The combination of standing and lack of movement, especially if combined with the hear, is guaranteed to make my knees swell horribly. A good if not exaggerated example is Flight of Passage. By the time one simply gets up to the show building, that's a lot of walking to then stand for quite some time in the queue and preshows. It's also not feasible for me personally to roll a chair toward (yes I know there is at least the possibility of powered chairs).
So, all that said, there is no longer a box for the parks to check for me that is genuinely helpful, since I'm told I'm considered a general mobility disability (which is technically not false, while also not true). I've had/chosen to cancel an upcoming trip to see how things shake out and for the cost/benefit of going under my particular circumstances.