That's certainly an interesting way of getting customers. Employ people, have them quit, they get hired into a position that has the ability to give their old company money.
If you run an organization that experiences the phenomenon of a lot of an organization's alumni become customers, then this is a pleasant and welcome side effect of what is described in this article.
Rather, it's simply that they're already aware of their old employers strengths and weaknesses, so vendor evaluation is made a lot simpler.