Homebrew [1] suffers from the same issue and it's horrible. What the hell is a keg, a cask? what is pouring? a cellar? what? I've been using it for years and I haven't bother to find out, but the fact that it's not immediately obvious is a sign of bad UX IMO.
Their usage of cookbooks and recipes is actually fine. Kitchen can be confusing sometimes but generally still fine... Knife is the most confusing of all. But what I really hate about Chef terms is they make searching with DDG really difficult.
I haven't even thought of rubygems and I deal with them every day. I'm curious now - they don't seem like a comparable issue for some reasons. Maybe because it's just one level? The language is Ruby which is arbitrary and the packages are gems which is connected in naming, but there's nothing more in language itself, right?
1: https://brew.sh