It doesn’t do anything, but neither does voting for a Democratic president in a non-swing state. They could just leave the box blank too. They’re not choosing “should I check the president box or talk to my neighbors”, they’re at the voting booth, presumably because other races matter, and filling in the box because it’s there. None of the options in that race matter and the comment you’re replying to is explicitly about how it doesn’t matter, so why are you even complaining?