Dollar to a donut there is a machine with IBM on it backing this up. At a prior life the ultimate reason why "you can type as many characters as you want but only the first 8 matter" came down to passing the login auth to a mainframe which only took 8 characters. Yes in EBCDIC, glad I never had to actually interface with them much, except for having to deploy ftps (ftp with ssl encryption, its an abomination, all due to no sftp on the mainframe at the time).