Or maybe, just maybe, really big corporations that make software solutions are often really big because their solutions are, if not feature-wise the absolute best, by far the most stable and reliable?
If one were to buy your argument, that would be like saying that businesses buying the Google Apps suite is nonsensical, because the only reason you'd ever use Google is because you're a "careerist" that "only know" Google.
That's obviously not true, Gmail and the rest of the Google suite have been market-leading for many years, because they are good solutions that solve real problems. Presumably the same thing goes for the Microsoft Office suite, and so on.
