The 2 degree thing gets stated all the time - and it's wrong. I once took a number of spindles and clamped their tapers together. Mavic, ISO and pre-ISO '80s Campy all were the same - the spindles remained parallel when their tapers were clamped together. Then I tried the same with a JIS and ISO and the taper difference caused the spindles to not be parallel.

Just because someone put it in a book, it doesn't make it true.