It's not really extreme. You can, and should, easily provide globals through attributes on classes and modules (which are globals themselves):

    module Foot
      @size = 10
      class << self
        attr_accessor :size
      end
    end

    Foot.size = 8

ActiveSupport gives you "mattr_accessor" and "class_attribute" to accomplish the same thing with less code.

In my opinion, class/module-level attributes are useful enough that it ought to be provided by the language itself.

Edit: Come to think of it, most people, that I have seen, use globals to set constants. That currently has perfectly good syntax:

    module Foot
      SIZE = 10
    end

    print Foot::SIZE

Sans ActiveSupport, you can achieve the same things by just opening class/module eigenclass:

    module Foo
      class << self
        attr_accessor :bar
      end
    end

    Foo.bar = "baz"

Sure, but wasn't that exactly what I wrote in my first example?

Oy, it is. Sorry; my brain is apparently missing its reading comprehension hat today.