The Land of the Free

Question: Why can't America have its own pantheon?

Depends on what you're asking.

If you mean native American mythologies, they do have their own pantheons and many people would really like to see them added to Scion! The core setting comes with only one American pantheon, the Mexican Aztlanti, but there are tons more native religions scattered all across both continents of the New World, from the Inuit gods of frozen Alaska and Canada to the vibrant panoply of North American pantheons (Cherokee, Zuni, Navajo, Algonuin, and a pile more) to the wideflung Inca empire down in South America. There are literally more Native American pantheons you could examine for Scion than there are currently published pantheons to begin with.

The problem is usually that they're so wideflung and that there's so comparatively little knowledge of them that many people aren't quite sure what to do with them for Scion. Some compromise by creating one "American" pantheon with figures from several Native American peoples included, but doing that would be a bit like creating a European pantheon with Thor and Zeus and Manannan mac Lir all part of the same "pantheon". Others just figure out the specific gods they want to use - Coyote and Sedna are popular choices - and don't worry about the larger cosmological world of the Americas. It seems unlikely that White Wolf will release much for the Americas any time soon, but we can always keep our fingers crossed (and, if you feel like it, send them a message to let them know what you'd like to see).

If, on the other hand, you're asking about America in the sense of apple pie, stars and bars, Norman Rockwell and the United States, that question's easier to answer: "America" can't have a pantheon in Scion because it doesn't have one in real life. It literally doesn't. The North American countries are extremely young in Scion terms, founded barely over two hundred years ago, and they have never had their own polytheistic religions the way the ancient territories of Europe, Africa and Asia have. There are no American gods other than the native ones that preceded European settlement, which is why Scion: Companion's Yankee "pantheon" was cobbled together from folk heroes and vague concepts, most of which any Hero-level Scion could equal or top without even having to try very hard. You can certainly do things with American heroes and folklore in Scion, just as you can with any folklore anywhere... but there are no gods or deities in it, so what you can't do is create a compelling divine pantheon that is anywhere close to comparable to the others in the setting.

I've never been quite sure why you'd want to, anyway, when there are so many cool world mythologies still left untouched in Scion. The hell with Johnny Appleseed - show me some Viracocha, Sedna, Erlik and Teshub!