Unfortunately, we’re talking about web developers who don’t seem to understand basic principals like avoiding namespace pollution. I mean, how can you even have a conversation with someone with such a misconception of good practices?
I was really hoping that someone with such a worthy track record would have seen the light by now. Luckily the require.js guy himself is pushing for AMD support in Underscore with a new pull request. Once that is pulled in, it looks like Backbone is next on the list.
Since the next version of jQuery will have AMD support, I imagine that the rest of the libraries will follow since they seem to look up to jQuery for best practices.