You are right, I'm pretty sure everyone who is a professional programmer uses homebrew, it's amazing.
However, coding to 1.8.7 lets those who aren't hardcore rubyists currently enjoy a gem they may otherwise not be able to without having to deal with or even know about rvm or rbenv.
There's gentoo/alt and fink which predates DarwinPorts. I'm sure there is even a pkgsrc user out there. I've occasionally used this one called make. It's sort of a meta language to homebeer. In fact it comes in two flavors pmake and gmake. =P
