there is absolutely NO NEED for simcity 5 to have been purposefully designed to require publisher operated servers to run other than to implement a harsh DRM scheme.
we played sc2000 on a 33mhz cyrix slc (essentially a 386sx that spoke i486).. sc3000 on a 133mhz pentium (non mmx version and original win95 no fat32).. and sc4 on a 550mhz k6-2 (2000, later xp).. the slowest bit of any of those games on any of those systems? the fucking cd-check drm for sc3000 and sc4.
things have sped up just a tad since then... not just raw cpu power but also the pc's subsystems (ram, hdd, graphics, etc).
even with neighboring city (region) math thrown in, i think a simple 2005-07 dual core desktop (e.g. comparable to pentium e5200 or first-gen dual core athlon, which is on the box as the 'minimum') with just 1 gig of ram available to the game (i.e. as little as 2 gig total, also on the box as the 'minimum') would be more than enough to handle all of the math for sc5, AND host multiplayer besides.
if the cpu requirements are so great that EA thinks server-based calculations are the only way to go... what kind of horsepower do they have on those servers if they do what even an old pentium e5200 can't do on their own? holy shit. they didn't charge nearly enough for the game if they're dedicating entire xeon server cores and gigs of ram to each player.. OM-FUCKING-G.
i guess the server actually plays the game and the the dual to quad core processor required or recommended by EA on the box is solely to run the fucking DRM