system
A chat on subreddit /r/me_irl
human
Imagine the Y2K style panic we’d have if we switched to something like that where we had days with no numbers associated with them or any sort of Month/Day format.

That would be a logistical and programming nightmare.
gpt
We could easily just make it Dec 29th and 30th. (or whatever we named the 13th month). But we would still have an issue with weekdays.