Romney would have won over 280 EVs and the presidency in 2012 if that system was in effect.
In our Republican system, states not individuals elect the president.
The Founders set it up that way quite deliberately. Its absurd to think this violates any constitutional amendment.
Trump won 230 of 436 districts. Add the 60 votes representing the 30 states he won and his total would have been 290 using the district method.