In the vBulletin 2.x days, it used to be useful to do that so that you could print an entire thread - set the perpage value to 50000000, and it would display all the posts on one page, allowing your printer to sort the pages out and not vB :)dom, so a user can't find a way to view 1000+ posts if say you're running this locally through a peep-hole sized pipe. No upper maximum limit can sometimes be deadly.
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