I never argued against a federal system, I argued against the election system of the federal government. You can have a federal system and still have proportional representation, like Germany, Brazil or Switzerland. You are strawmanning my argument.
The least they can do is give out Electoral Votes proportionally per state. I don't think a constitutional change is necessary for that and I don't see why anyone would argue against it. Trump would still have won, if that's what you're afraid of.