>> Why? Your hands don't work?

That’s quite rude and unnecessary.

To answer the question, there is an infinite number of things I can do with my time. Learning that particular manual skill, especially when there is a very simple alternative, just doesn’t seem worthwhile to me.

Rude? Just asking because 10min to sharpen a knife every 3-6 months is not that big of a commitment, unless your hands don't work properly.