There are a lot of half-truths going around about photography. Generally, the various photographic equipment companies spread one or two of them, and then the various photography magazines and megasites play along because they realize that to go against what the photography companies want is a great way to not get access to the latest and greatest for review.

One of the central arguments of the 4/3rds mount was that digital camera sensors were destined to stay small, thus, a new mount for these smaller sensors, with a smaller lens throat and registration distance so that the lenses could be smaller and lighter, only covering that 4/3rds mount size. Of course, Olympus kinda screwed it up.