Earlier quoted context omitted.
"UTF-8 was first officially presented at the USENIX conference in San Diego, from January 25 to 29, 1993" ( https://en.wikipedia.org/wiki/UTF-8 ) Hey team, we're working to release an ambitious new operating system in about 6 months, but I've decided we should burn the midnight oil to rip out and redo all of the text handling we worked on to replace it with something that was just introduced at a conference.. Oh and…
Interestingly, there is another story on the HN front page about Steve Wozniak doing exactly that for the Apple I: https://news.ycombinator.com/item?id=45265240
Changing an in-progress system design to a similar chip that was much less expensive ($25 at the convention vs $175 for a 6800, dropped to $69 the month after the convention) is a leap of faith, but the difference in cost is obvious justification, and the Apple I had no legacy to work with.
It would have been great if Windows NT could have picked up utf-8, but it's a bigger leap and the benefit wasn't as clear; variable width code points are painful in a lot of ways, and 16-bits for a code point seemed like it would be enough for anybody.