Question For The Chefs Out There

Why the hell is Cream of Tartar a powder? It took me ten minutes to find the damn stuff in the grocery store today because I figured it would be in with the various little bottles of extracts, but it was actually over with the paprika! This makes no sense to me. If you're going to call it a Cream of Something, shouldn't it have a texture similiar to, I don't know, cream?