This ensures that wear is even which helps with the longevity of the parts and also ensures smooth-running as there will be no uneven wear on one part of a cog. Another side effect is to spread oil evenly across all teeth in a reasonably short running time.
I cannot see how a mobius gear would offer any significant benefits over this. Most cogs are already machined to fit each other neatly, and the problem with fan belts (uneven wear) doesn't really apply to gears.
Try it out on a piece of paper and see for yourself (that's what I did).