This reminded me of my last place of employment. We didn't use any form of version control system. Instead, every time we changed a piece of code, we commented out the existing code and left it there, next to our revised code, along with a START and END comment including the coder's initials, date, and the ticket or project the change related to.

Frequently changed parts of the code were a hideous mess of 90% comments to 10% code. And then occasionally we'd just rename an entire file by prepending 'old' to it and starting fresh with a new file.

That place was such a learning experience on the concept of technical debt. But at least I got a fun talking point for my resume. "x++, is that a typo?" "No, sir..."