How is it not? In the not so distant past of the 1930s there were political parties advocating for the mass killing of people with disabilities, or at least the sterilization of those with heritable disabilities. There have been real campaigns in that period that did this type of forced sterilization, especially in some mental hospitals. You'll still find people espousing such beliefs, thankfully at the fringes for now.

Accessibility is the opposite position of that - but it's by no means a universally accepted good, unfortunately, especially when it requires extra effort to implement.