Yep. America used-to have wheelchair-bound president 100 years ago, for Christ's sake. Now, it would be completely impossible. Presidents have to look good, or at least healthy. Even the senile Joe Biden is actually looking pretty crispy.

FDR and his administration went to great lengths to hide the wheelchair. They even made a panel for the resolute desk to hide FDRs lower body when seated. Imaged mattered then as much then as it does now.

https://en.wikipedia.org/wiki/Resolute_desk

Wheelchair users have been elected to Congress in recent times. It's not impossible that one could make it to the Presidency. We just don't have enough data points to draw firm conclusions about how that impacts electability.

FDR (not quite 100 years ago) was wheelchair-bound but very cagey about it. And FDR was hardly fifteen years in the grave before Nixon lost a TV debate to Kennedy by looking pasty.

The senile Joe Biden?

He's 79 years old. Senile means, as per the thefreedictionary.com: "of, relating to, or characteristic of old age".