How about requiring a $5 deposit to post, refundable at the end of your posting tenure, and confiscated on falling foul of the guidelines? An additional benefit would be fewer low content posts
Making people pay to comment removes certain types of low quality and spam comments, but I believe it can actually worsen polarization. Most people with moderate points of view aren't going to be nearly as motivated to comment as those who have extreme views, and therefore will be even less likely to do so with more barriers in place.
Metafilter has done this for years quite successfully.