Makes it much harder to just start and plaster everything with big planes.
You actually have to THINK about what you are doing, what your Long-Range plans are going to be, and BUILD what you want to fly. Just like a REAL airline of that era would have to.
What do you WANT, vs. what you can AFFORD really comes into play. The more successful companies can plan farther into the future, while the smaller one's will have the advantage of plentiful, CHEAP aircraft out of the gate.