And people have such a poor distinction of exactly where the limits lie.

My mother was blind. I was able to teach her how to glue up PVC. (For those of you who don't know--it's a don't-touch, less than a minute of working time and sets even faster if assembled and not moving.) Could she build things out of PVC? Yes. Could she repair a pipe? No. She needed everything perfectly arranged, an existing pipe wouldn't be perfectly arranged. And when my father died people wouldn't believe the big power tools in the garage were hers, not his. (Stuff where she could measure and clamp, hands only on the tool's controls.)