[NoOn3]

If someone create a new MMORPG in which rules changes a little every day or several days in unpredictable manner then no one will be knowing the BEST way to play or at least harder to find the BEST way. But maybe there will be no balance.

[JoshTriplett]

I don't think that would work: either the rules change little enough that you can still document meta-strategies, or the rules change too much and players can't learn them either.