[mcphage]

"Doing X", and "Managing people doing X", are two pretty distinct skills—and interests. If you find someone really good at doing a thing, why would you pull them out of that position? Odds are they won't be good at it, and they won't enjoy it. There are people who enjoy both, but they're rare.

[melling]

Exactly. Find someone not good at X then have them manage a dozen people doing X and pay them 50% more.