Defaults matter.
So does knowledge of your stack. Rails default settings are for development on one box, it expects you to look over the settings at least once before you push to prod. I can't blame Rails for not having "client demo for 20 people" as the default settings (and I also can't really blame GP for not thinking about Rails configuration too deeply as a junior engineer, that is on the more senior engineers on that team who apparently completely forgot to verify it worked before doing the demo).
I really, really dislike Rails for any number of reasons, but not having spent the time to understand how to set it up is not Rails fault.