First of all I agree with pregnant people not riding those rides, however, if people who have back pain choose to ride the rides even though they know the potential risk, thats up to them. My bf is a doctor and he knows his limits with his back and I would never make him do anything that would be an issue. We didn't scam the system, he has a medical condition that is not visible and the GAC is there to provide assistance to those who need it, we didn't use the card for every ride, like I said it was at the end of the trip because he was getting worn down.
People that have pain doing one thing like standing still does not mean that they will have pain when walking, so yes in some ways "skipping" the lines may in fact help. I have never had an issue waiting in line for rides, I've stood in line for TSMM for over 3 hours without complaining. If someone is physically able to walk, but has pain when standing or needs to take occasional breaks, they shouldn't be forced to use a wheelchair. And also, using a wheelchair would not be more comfortable in all situations, because some people with back issues have more pain sitting for extended periods of time so that would defeat the purpose of being in a wheelchair.
They list those medical warnings to avoid lawsuits, its to cover their a$$. If people were to follow all those guidelines, no one would be riding anything in Disney because a lot of people suffer from back pain, motion sickness, heart problems, etc. I know I wouldn't be able to ride anything because I have a back problem and knee problems from doing gymnastics for 16 years.