While I admit to playing nuclear Risk, playing Monopoly, Careers and Life simultaneously does put you into a very ... special ... category.
As far as the recent thread trend, versions are just an indicator that the game rules are pretty compatible for most people, an indicator that has slowly emerged over time. Getting caught up on exact details doesn't really matter. Version numbers aren't arbitrary, doesn't mean they aren't also part of marketing the game and an attempt to indicate how easy it is to mix and match. Unless you're Cadence, master of mish-mash.