Well, Discourse is pure JavaScript so everything is possible 
Disclaimer — I don’t code.
To get pagination you have to load headers of all topics. Otherwise you can’t know if a topic would be on page2, 79 or 2298. But that order is not fixed as it would be on blogish sites, like WordPress.
Everytime somebody is commenting, there is auto bump etc. that order shall change. So you should build all sub-pages everytime when something happends. I’m guessing that is really expensive.
Plus unnecessary. What does an user get if she/he/it knows there is 26768 sub-pages?
As I said I don’t code. But I’m doing UX/UI/content creating and quite often I have to say to a customer that wanted thing is impossible or really bad idea.
So. What is the real need why you should build up pagination on latest?