In long threads I often have to search, who said what and when. This is of course solely caused by my age related dementia. Maybe also to quote an early post. If the entire thread is on a single page, I can simply press Ctrl-F and search what I'm looking for. Way quicker than having to resort to the forum search for this purpose.
On the other and I can understand, why some prefer paged threads. The perfect compromise for me would be, if it could be made a profile option. Beat me, if it already is and I just didn't notice, yet.