This article really rings with me. It's odd, because usually employers say that they prefer generalists who are smart and quick learners, but in the very same job ads they want e.g. "at least 5 years of Rails experience" for any somewhat senior position.
The best generalist fit is leadership of diverse specialists(note leadership not management).having problem domain experience in divergent areas you can use people with deeper knowledge in specific niches and weave things together.
However most companies regard that as an MBA problem domain.