"Not so sure that's the driver here. Many devs have bought into the iOS ecosystem. This certainly isn't cheap: macbooks, imacs, iphones, ipod touches, ipads. It's also a pretty deep dive to get into."

There's a pretty big difference here: lack of choice. If you want to deploy native apps to iOS, you literally have no choice but to get into that world. If you want to deploy web applications (as many startups, especially HN startups do) there are dozens of options to choose from aside from buying into a single vendor's full stack.