1. What the hell happened in 1990? Yield curves were pretty flat before that, and much less flat after that. 2. Anyone buying 30-year treasuries at 1.69% during 5% inflation is out of their fucking mind. Bitcoin is infinitely better.
Japan started exporting deflation in the 1990s after their bubble burst. This was joined by Europe in the 2000s. We could get more from China.
What do you mean by exporting deflation? Taking on so much foreign-held government debt that it meaningfully reduced the money supply in the rest of the world?
Interest rates have been on a secular decline since the 13th century. Higher rates in the late 70s/80s was just a blip.
Some financial institutions are required by law and charter to hold a certain percentage of their assets in Sovereign Treasuries. Think Life Insurance Companies.