"Boo outgroup" partisan fluff aside, nobody actually genuinely believes that. And the powers of US president, while great, are nowhere near the dictatorial powers of Chinese Communist Party and its General Secretary. It doesn't mean US federal government isn't grotesquely overpowered (it is) or partisans don't abuse legal and regulatory system for partisan purposes (they regularly and routinely do) - but it's not nearly close to the system China has where anybody who crosses the Party will be murdered or imprisoned or pushed outside of the country without any recourse. We do have some elements of these system, but on that road, we are still way behind China - and maybe we have time to turn back, if we wanted to.