On the surface, you're right, but in all of those systems, you still need a governing majority. In parliamentary systems, coalitions are formed after the electi

On the surface, you're right, but in all of those systems, you still need a governing majority. In parliamentary systems, coalitions are formed after the election. In America, the coalitions are formed before the election. The two major parties, really, are big tents comprising a handful of minor parties within them. You can see this manifest in the ideological breadth of representatives within the same party, across different constituents. In a parliamentary system, some of those constituents would elect the same representative, just under the banner of a more appropriate political party.