_Ruby_ devs are going to be attracted to Homebrew because it (and the "recipe" for building every Homebrew package) is written in Ruby. The test of MacPorts is how many non-Ruby devs use it.
Whether or not anyone uses it, it is still linked from https://developer.apple.com/opensource/ and was part of Apple's open source strategy several years ago. Regarding Ruby, Apple backed the MacRuby implementation for a while but that also petered out.