For one thing, people are tired of not being treated as the authority on their own bodies and experiences. We hope this is obvious, but someone with a chronic illness or a disability is inevitably going to know a lot more about it than someone without—they’re the one who has to talk to doctors about it in detail and try different methods for managing it, so they’ve probably already tried doing some stretches.
Along similar lines, seeing somebody once doesn’t tell you everything there is to know about their circumstances. Somebody who can walk but sometimes uses a wheelchair might need to avoid more serious symptoms caused by walking, and using a wheelchair gives them more freedom of movement than the limited amount that they can walk.
On the other side of the coin, just because somebody doesn’t seem to require supports when you meet them doesn’t mean that they have no significant disability and appearing “normal” isn’t a challenge in itself.
