I really don't mind the individual pages and I don't think it really "pollutes" the browser history either. Rather, I think it makes it much easier to link a friend to a specific comparison.
For all valid states/URLs, users expect that the browser's back and forward button work as expected, and that they can save or send that link to others.
Users expect the back button to work for page transitions, not state/UI transitions. And again, this doesn't impact the ability to send the current page state as a link whatsoever.
For what it's worth, pure state changes (that don't occupy a page within the router) do use history.replaceState though.
I understand that this wouldn't be the case if I approached the design as per the rest of your feedback; placing a lot of this content within a single view could be done. However, the UI/UX is designed to be shallow, minimal and mobile friendly.
For example, while I could put weapon selection in as a filter and add controls to toggle between data views - creating a single powerful view - this doesn't actually accomplish much other than trading valuable space for increased UI complexity to avoid moving views.
Admittedly, I see this through a different lens as I'm aware of the amount of controls I need to somehow fit further down the line to support upcoming features. A desktop only site would be very different!
I appreciate your feedback; it's great to see things from another perspective.