... any discrepancies in the use of "year" as a 4 digit number vs a 5 digit number, are entirely a display issue (front end).

That's exactly how I read the meme. It would still require a change.

Whether that is displayed to you correctly or not, doesn't matter in the slightest. The machine will function even if you see some weird shit,

I'm not sure if this is some nihilistic stuff, or you really think this. Of course nothing actually matters. The program will still work even if the time is uint32 instead of uint64. The machine of course will still work as well. Shit, your life will go on. The earth continues to spin and this will for sure not cause the heat death of the universe. But aside from actual crashes and some functionality bugs, UI issues should be the ones you worry about the most. If your users are a bank and they need to date the contracts, and you only offer 3 digits for the year? I think you'll agree with me that if users don't like using your program, it's a useless program.