Agreed with most of this - with the additional caveat that the political right and left need to take joint responsibility for the discourse. The political left and poltiical right are kicking with equal venom in opposite directions - and fueling each other's core base - including here on Medium.
It's very easy to see this as a problem with Freedom of Speech, and not an erosion of the standard of discussion. Lots of people, including on this platform write inflamatory posts, knowing they'll get high levels of support within their echo chambers - but without thinking through the consequences of what that means long term.
What needs to be promoted is both a freedom of speech and the recognition that certain positions on both sides are intellectually backward. That's very easy to do with the opposition, but not quite as easy to do when you're looking at the demagogues you agree with.