Why use output buffering in PHP?

Question

I have read quite a bit of material on Internet where different authors suggest using output buffering. The funny thing is that most authors argument for its use only becaus

Answer 1

We used to use it back in the day for pages with enormously long tables filled with data from a database. You'd flush the buffer every x rows so the user knew the page was actually working. Then someone heard about usability and pages like that got paging and search.