This isn't necessarily true everywhere -- when I lived in Memphis, TN, I often felt that I was dooming my professional career as, every time I ran into a challenge, I'd fork my efforts and start tackling it. This means that I was getting skilled in (but not expert in) a wide variety of things. In short, my knowledge set was very wide, but somewhat shallow.
It wasn't until I moved to the DC area that I realized there's not only a market for that type of person, but a fairly lucrative one.
There are other tracks too, Architect, Management, whatever... whereas the scale repairman who can weld, machine and EE on a scale system is not exactly limited to just working on scale systems, but isn't necessarily opened up to as many positions as with software dev.