The hamsters used to automatically nest internal quotes, but the feature was dropped in one of the vBulletin updates (I think it was when we came back from the Winter of Missed Content, about two years ago). It makes for much cleaner-looking threads, since a lot of folks habitually “quote” an entire post, unedited, before making their own reply. The exponential growth of those posts–as folks merely continued to quote the responses to the responses with all the old responses still intact–got to be pretty ridiculous in many instances.