You're actually incorrect, and yes Disney does. Disney has alternative arrangements on each and every ride depending on your limitations. You are missing that each ride has accomodations for those who are physically disabled. DAS is for those whose disabilities are not met by using a wheel chair or ECV.
Other Considerations
A Guest whose disability is based on the necessity to use a wheelchair or scooter does not need DAS. Depending on the experience, Guests utilizing a wheelchair or scooter will either wait in the standard queue or receive a return time at the attraction that is comparable to the current standby wait. If you’re a Guest who has mobility questions or concerns, please view Services for Guests with Mobility Disabilities.
ADA does not limit as much as you think. Even ADA allows one to ask a couple questions about service dogs and what they might be trained to do. ADA from their own words says The Americans with Disabilities Act (ADA) prohibits discrimination against people with disabilities in several areas, including employment, transportation, public accommodations, communications and access to state and local government' programs and services.
So under ADA
Title III (Public Accommodations)
Nondiscrimination on the Basis of Disability by Public Accommodations and in Commercial Facilities
This title prohibits private places of public accommodation from discriminating against individuals with disabilities. Examples of public accommodations include privately-owned, leased or operated facilities like hotels, restaurants, retail merchants, doctor’s offices, golf courses, private schools, day care centers, health clubs, sports stadiums, movie theaters, and so on. This title sets the minimum standards for accessibility for alterations and new construction of facilities. It also requires public accommodations to remove barriers in existing buildings where it is easy to do so without much difficulty or expense. This title directs businesses to make "reasonable modifications" to their usual ways of doing things when serving people with disabilities. It also requires that they take steps necessary to communicate effectively with customers with vision, hearing, and speech disabilities. This title is regulated and enforced by the U.S. Department of Justice
Given there are rides that some wheelchair bound people cannot ride, they don't have to allow everything. In fact reasonable accommodations could be much different than you think.
I've done it 3 times online in the last year. Last being in April for a June trip. They were kind 2 of 3 times but never did they brush off. I was asked why i need special accommodations. YMMV as I said but I'd be prepared for more in the future. In fact you can find old DAS discussions and see stories of issues I've even had. Personally I find it disappointing if they weren't asking questions as they should so people would stop acting like it's easy to abuse.