[Al-Khwarizmi]

I think it's probably because it's very difficult to understand a pure math talk if you didn't already have significant understanding of the subject before the talk.

I don't work on pure mathematics, but I work in a field of computer science where there is both theoretical and empirical/applied research, and I do, and enjoy doing, both.

However, when it comes to attending talks, I do go to a lot of talks on empirical subjects just for fun, but I hardly ever go to a highly theoretical talk for fun. I only do that if the talk is highly related to the specific work I do; if you see me in a theoretical talk otherwise, it's probably just for social compromise.

The reason is that I can perfectly understand the gist of an empirical paper in 20 or 30 minutes, where there is no way I will understand a piece of theoretical research by listening to a talk if I haven't gone through the paper carefully before (and if you have done that, there is often no point in going to the talk anyway). Honestly I think the talk format doesn't lend itself too well to highly theoretical work. I have learned a lot about empirical research and obtained many useful ideas from talks, but in the theoretical field, the useful ideas and insights I got from talks are few and far between, and I would probably have obtained them more efficiently from reading papers anyway...