[PurplePanda]

Maybe they've been there before and happen to remember "page 10".

Maybe someone else has been there before and told them "Go to page ten".

Maybe you know that there are 20 pages, and are looking to find the median, or are just informally playing around, looking at the distribution.

Same as you'd do with an interesting page of a book. I don't think I'd stop using page numbers in dead tree books if they somehow came with filters.