And to that end, they specified that Presidential Electors should be appointed by state legislatures. They didn't go so far as to prohibit choosing them by popular vote (because they left it up to the legislatures to decide), but having the People choose the President is clearly not what they had in mind. What they were actually going for was something more similar to the way parliamentary systems choose the Prime Minister (by vote of the parliament itself). The only difference is that they wanted the state legislatures to choose instead of Congress, for added Federalism. (That's also why Electors are a thing, by the way: they couldn't have 1 vote per state legislator because different states had legislatures of different sizes and they needed to make it fair between states, so instead they had each state legislature choose a number of Electors equal to that state's representation in Congress.)

Same with Senators, too: those were supposed to be appointed by the state legislatures instead of the People directly for basically the same reason.