Lol, that's completely silly. Who even knows if we'll still be using the same calendar in 8,000 years? Y10K is not worth dealing with until the 100th century.
Does preparation become pointless sometime after 8,000 years from now, but before 92,000 have elapsed?
Is the hypothetical problem so bad that solving it is worth the ambiguity between octal numbers and the extra effort for readers to parse 02022 as year?
Instead of just sitting around discussing vague ideas they thought it would be interesting to design and build something to showcase their ideas, so the "ten thousand year clock" was proposed. It is amazing how many problems you have to solve to build a clock that has even the slightest chance of still be running ten thousand years from now.
A side effect of the clock project was that some of the dates involved would have five digit years, so they thought using five digit years for current dates would be a good way of shocking people and exposing them to their ideas.
sprintf for a better tomorrow.
It's also annoying to read. It costs a half-second to think every time we read a year. That's rather reader-hostile.
Also, surprisingly, it flushes out the people who would have supported Turing's ultimately fatal prosecution because OMG he's such a weirdo, before their support is required for anything important. It makes super clear the distinction between who's here to have interesting discussions and who's here to attack other users.
"it flushes out the people who would
have supported Turing's ultimately
fatal prosecution [...]"