@cstross
My dad was in a plane crash in Moscow in the 70s, due to refueling, and we visited in the 80s.
Even then I wondered why it wasn't safe to put a visa stamp directly in the passport. Nowadays if I did ever have to visit the US, I think I'd want a clean passport to do so with.
It's been increasingly difficult to see the difference, unless you are part of the ruling classes, or can fake it for just long enough.