Because, on average, each town gets 8-9 tiles and even if you give the wonder-building town the best 12 tiles, it's at the expense of the other six low-corruption town so one town alone will have a reasonable shot at a wonder. With CXXXXC, at least the capital plus the first six, low-corruption cities will have a choice of the 12 best out of on average 19 tiles per city. Chances are with CXXXXC that the wonder-producing town(-s) will produce substantially more shields per turn, = have a better chance of actually completing the wonder, even if you use prebuilds. Their production won't be tied up for as many turns either. Early MA. The CXXC-player has the choice of which of Sun Tzu's, Leonardo's, Knight's Templar, Sistine or Bach's to go for. The CXXXXC can attempt at least two if not three of them. At least at levels below deity. Ah. Of course! You could always let the AI build them for you! But what if the most distant AI is the one that completes the wonders you want and need and won't be able to conquer until late IA?