It's been around since before 1992. Users can have files and folders, of course, including 'incoming folders'. It has a primitive filtering capability, which can sort incoming mail into the incoming folders. One can, and is advised to, use procmail for this purpose.
Folders support message sorting and selection based on various criteria.
This is useful for searching through archived messages. Sub-folders and folders on other servers are supported. Pine includes good support for IMAP and local mail spool. It can access a couple of different mailbox formats. In general, it appears to be very compliant with various RFCs.