Poe's law. There is no parody so outrageous that someone couldn't make the same argument either sincerely or as a troll.
And for what it's worth, I consider myself reasonably capable of considering arguments in favour of opinions that differ from my own. On many occasions I have changed my mind about an issue based precisely on arguments that persuasively challenged my assumptions or beliefs. I just have an expectation that those arguments should not be ridiculous.