this is the reason in my opinion and experience
as a lead dev in a rather complicated environment I tended to solve the problem many times where some identifier was used. short deadlines and no specification made us solve the problem quickly, so some shortcuts and quick actions were done. this identifier gets asked about later and super overcomplicated explanations given as a reason by people that don't know the history.
...and the history is often like 'they mounted stuff to /usr because they got a third drive'. and now, people even in this thread keep giving explanations like it's something more.