"First, the "forever" standard is part of ERISA - maintain records as long as necessary to determine benefits payable - and frankly, it isn't that burdensome. Buy another hard drive or rent some cloud space on another server."
Sure, easy to say now! We are all talking about something that happened (or, possibly, didn't happen) 20 years ago. Back then, computers had hard drives that could hold 20 megabytes (soon to jump to over 100!), and the only clouds were in the sky (and, depending on the season, might rain or snow). If you tried hard enough, you could save documents on floppy discs that held 1.4 megabytes of data. Most records then were kept on paper.
So if the employer wanted to keep complete records forever but 18 years ago they were all destroyed in a flood or fire, how does the employer prove that the person has already been paid? And is "forever" forever when someone's benefit was already paid out?