this is not the d3 they have been working on since day 1.
original game was dropped
they started making what we have now
decided it was not blizzard quality a year or so before release and started over then released it early.
Look at the title of that thread. "Seven Years in Sanctuary"... 7 years for the current iteration of the game. They released a demo video in 2008 which gave them 3 years to develop the game into a demo-able state (plenty of time), so the math adds up.