The "Social Model" of disability says that people who have disabilities are more harmed and hampered by discrimination and physical barriers in the community than by their actual bodily impairments. This is a pretty widely-accepted concept among people with disabilities and others, especially those who are activists or who have studied and thought deeply about disability issues. Although you don't often hear it outright, I suspect that many people who hear about the Social Model of Disability find it hard to swallow. Maybe they look at their own impairments, or those of friends and family, and feel it's just going too far into abstract theory to say that being paralyzed is fine, while the real problem is lack of curb cuts.
Put exactly that way, I agree that this sounds just a bit off.
The thing is that certain situations prove in a very concrete, very non-theoretical way why the Social Model makes sense. A supermarket cashier who uses a wheelchair and has a wheelchair-accessible work area is, in the practical sense, less disabled. She can physically do the job, and she can earn her own living. If her work area is made inaccessible … a counter made too high, a desk made too low, wheelchair maneuvering space narrowed or blocked … then she is, in fact, more disabled than she was before, even though her physical impairments haven't changed.
When a promising young person has a car accident resulting in a permanent disability, it's big news in a community, a story that makes people feel sorry and sympathetic. When a disabled worker is carelessly squeezed out because of poorly planned, entirely preventable physical changes in a workplace, the affects are, in a very real way, the same. Those are the times when the Social Model of Disability is proved correct and most relevant.