Unfortunately the answers to that question focus on critiquing how the rankings came about, which are not really relevant to what I want to ask. Clearly I worded the question poorly. I've already tried to focus the question by editing out the mention of Zhejiang University (depressingly this still led to responses about the anglosphere and whatnot even though I'd left in a note that I'm not interested in cultural factors), but it's evidently not good enough and people continue to interpret the question in a different way.
What I really want to ask (as I wrote in a comment to Thomas's answer):
Assuming you are an academic, you'll have some idea where the best research in your field is performed. If you next compare where that is versus where the top universities in the world are, you should see a positive correlation. The question asks why there is a correlation.
I don't think this question is salvageable unfortunately. What should I do now?
- Start another question with "is research at Oxford in general better than at Southampton?" If the answer to this is yes, then I can start another question after that linking to this question. However this seems like an overly narrow question since it explicitly names two universities only.
- Start another question with "why is research at Oxford in general better than at Southampton?". Same issue as the previous option: it's narrow.
- Start another question picking universities by THE reputation rankings, which might sidestep objections based on ranking methodology; however it's not apparent to me that the universities with the best reputations also do the best research (looking at the list itself, they should, but in a vacuum there does not have to be a correlation between the two factors).
- Do nothing and accept paul garrett's answer.
- Something else?