I find (after a verrrrry long time of arguing with people on the internet), when somebody acts as obtuse as the person you're replying to, they really aren't ignorant, they're trolling, or looking for an emotional argument. One of the common tells is making an obtuse statement that's fairly vague (to draw out responses) and then writing long replies to those that show much more cynicism/disingenous, which provoke people further, followed by "see! this is just an example of how deluded the people who disagree with me are!"