Mental skills (just like motor skills) also degrade with time. I can’t remember how to do an integral by hand anymore. Although re-learning would probably be faster if I looked it up.

Please don't think of this as moving the goal post, but back to maps and GPS: you're still doing the navigation (i.e. actual change in direction), just doing it with different tools.

The last time I dealt with integrals by hand or not was before node.js was announced (just a point in time).

Sure, you can probably forget a mental skill from lack of practicing it, but in my personal experience it takes A LOT longer than for a motor skill.

Again, you're still writing code, but with a different tool.