This is a(n) historical question, not a comparison-between-languages question:

This article from 2005 talks about the lack of a single, central framework for Python. For Ruby, this framework is clearly Rails. Why, historically speaking, did this happen for Ruby but not for Python? (or did it happen, and that framework is Django?)

Also, the hypothetical questions: would Python be more popular if it had one, good framework? Would Ruby be less popular if it had no central framework?

[Please avoid discussions of whether Ruby or Python is better, which is just too open-ended to answer.]

Edit: Though I thought this is obvious, I'm not saying that other frameworks do not exist for Ruby, but rather that the big one in terms of popularity is Rails. Also, I should mention that I'm not saying that frameworks for Python are not as good (or better than) Rails. Every framework has its pros and cons, but Rails seems to, as Ben Blank says in the one of the comments below, have surpassed Ruby in terms of popularity. There are no examples of that on the Python side. WHY? That's the question.