What happened was that the States, over time, delegated responsibility for elections to a host of lesser bodies like counties, cities etc, for political reasons. It’s much easier to rig an election in a smaller jurisdiction.

And when around 10 000 votes can win you the Electoral College votes for a swing state the temptation is high.

Incidentally, if you read the Federalist Papers you will discover that the rationale for this rather complicated system was to avert…foreign influence!