iTunes can register any number of iPods or iPhones, but is limited to five total iPads and Macs. Why in a decreasing DRM world, are we still faced with authorized caps?

If it has to happen, why not instead cap the numbers of concurrently playing devices. A single authorized account cannot play on more than 3 devices simultaneously, but you’re allowed to authorize any number of computers with your account.

As long as your Mac or iPad is online, it seems easy to control. If the devices are offline, so be it, that in itself is a restriction.