Is Oxbridge mainly for single subject passion - not for polymaths?

[waddauthink]

...only ask, as the more I read about the application process, it seems it's the case that students applying nowadays have to show an incredible level of passion and interest in their 'chosen' subject (supra curricular).

However, there are of course some extremely bright kids who are genuinely gifted all rounders, more of the polymath persuasion where they have strong interests across a number of subjects.

When reading about the famous scientists, philosophers etc of times past, many of those seemed to fall into the polymath category.

Is this not valued any more?

There are plenty of joint degrees as well as degrees like PPL or PPE at Oxford and the natsci tripos at Cambridge. The latter would appeal to people who are interested in more than one science.
People who are polymaths will have to specialize in something at some point. That doesn't mean they won't have interests outside of their degree subject. If they are mathematical, musical and interested in languages they could do a degree in Maths, play in the college or university orchestras to a high standard and also become fluent in a language.