Are you seriously making the argument that if Nazis didn't listen over seventy years ago that you don't need to explain things now? Because, what, only things that convince Nazis are worth saying, and because society is static over century-long timescales?!

Also, it's completely reasonable to expect disabled people to explain why they need other people to make changes for them. That's exactly what happened. The explanations were convincing, and now we have all kinds of access that we didn't in the past: the physical and moral necessity was clear.

I'm not saying that explanations don't exist. I'm saying that the emphasis is wrong: the emphasis, what is easy to find, includes a lot of stuff that exacerbates the misconception. It's reasonable to expect people to look for more detail, but it's also prudent not to point people down the wrong path starting out.