I know people bemoan the popularity contest aspect of this show (and all the other America Votes shows).Now I agree based on dance skills alone Marie should have gone home. But if I wanted a dance skill only moves you forward show (or the producers wanted that) they would run it like Project Runway where only the judges have a vote.
Once you let America vote you have to put up with them caring more about who they like and not who performed a complicated set of skills in the most technically perfect way. You get better ratings when America Votes, people become invested and keep watching and you make way more money so I don't see the end of popularity contest shows any time soon.
A lot of people like Marie. I don't know that it is enough to have her win, but liking someone isn't just about technical perfection for a lot of people. I sometimes enjoy a slightly less perfect routine when there is a lot of performance and personality that makes me really feel something.