Ongoing contracts (e.g. life insurance policies may last 40+ years). I did work for an insurance company once, and they had active policies started prior to 1940. There were electronic documents which dated back 30+ years.
While completed transactions may only need records for a few years, ongoing assets and contracts need documentation held for much longer.
Probably stuff to do with property ownership.
Last PC I saw in daily use with floppies in daily use was about five years ago.