I keep reading where people say that airlines like Spirit, Jetblue, Frontier, etc need "scale" to be competitive. United only has a 17% market share. How are they "growing too fast"? Aren't they just trying to achieve more scale? Domestically United is only the 4th largest airline. The answer for competition is scale, but apparently not if United wants more domestic market share?

When a business starts to approach diseconomies of scale you see declining marginal profits. Right now United isn't seeing that. Proof was leading 1st quarter profit in a quarter United is historically unprofitable.