The problem with political discussions is they:
a. Have almost no information in them. Often there are far more than 2 valid policies that could be considered for a situation, but the nature of USA politics mean at most 2 have any chance of being enacted. So it's literally an argument over 1 bit.
b. Most participants, even here on lesswrong, have been indoctrinated and totally convinced of 1-2 kneejerk slogans and have done no independent thought on it. For example of this I keep seeing coming up even though it's not a R/D issue: bring up nuclear energy around techies. You will instantly see a bunch of factually inaccurate propaganda they spout. Either it will be exaggerating the risks of radiation releases or a number of false claims about the benefits of nuclear power. (I bring this up because what is interesting is that both sides that typical reasonably educated people will take on this issue are false and essentially useless opinions)
c. All sides of the argument enter the argument with a deep set belief that will not be changed, and they leave with the same belief. So there was no reason to have the discussion to begin with.