I am agreeing with you as hard as I can.
That being said, there are incompetent developers who get a lot out of the exercise of “training-via-pairing”, and at least a few of them come out the other end as competent.
I find a lot of time, I’m either pairing, or running a group working session, not because it’s of any use to me, but because lord, the other folks need it. Somehow, they lack the ability to learn without someone actually directly mentoring them — and like the man said, you go to war with the army you have not the army you want.
The only time I start feeling a bit resentful is when I find myself teaching short-termers who won’t be around long enough to make use of their skills. We have a lot of contractors who are time limited to 2 years by company policy, and training them feels like pushing that same boulder up the hill that keeps falling down :)