The thing is, at one point in time, a large company like IBM would invest in its employees by helping them to develop their skills. Over the duration of their career, they could move within the company to put their evolving skill set to use. But nowadays, if IBM has a bunch of people with outdated skill "X" and they want a bunch of people with sexy, new skill "Y", they fire the "X" people and hire the "Y" people from outside the company. Or, more likely, acquire a handful of startups and small companies that specialize in skill "Y". They save themselves the trouble of having to teach the "X" people how to be "Y" people.