OpenStack is a large, complex piece of infrastructure software used at scale that many people, even on HN, will never experience directly. Why don't you hear about us much? Because people running at that scale frequently don't enjoy talking about the details of their infrastructure.
Ask the question next time you see something in a software tool, e.g. gerrit, that seems over-complicated: What can this software do because of this complication that I'm missing?
I don't think the tooling we use is what everyone should use, by any stretch, but don't assume things are being done in an antiquated way just because they're different than you're previous experiences or because they've been done that way for a long time.