I agree in general, but some communications platforms (like Reddit, and like Facebook...and probably like HN) can be more or less accomodating of "echo chambers" that validate and magnify extremist viewpoints. On the other hand, similar effects can nourish minority cultures and communities...it's a hard problem.

I agree that free speech is a good thing, and I think that "You have to take the bad with the good, because we don't agree on what's good" is a broadly useful philosophy. But systems which take in both bad and good, and strengthen the bad more than the good, are themselves bad.

If the extremes were banned, then the promoted neutral/centrist view would become extremist on it's own.

Cross-subrreddit trolling and genuine spills at least minimises echo chamber effect somewhat. If that was limited or non-centrist subreddits/users were banned, the centrist (or whatever was supposed to be OK) echo chamber level would go off the charts.

First amendment only applies to what the government can do. Private companies like Reddit, Facebook and Google have no responsibility to let you speak on their platform.

"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances."

https://www.law.cornell.edu/constitution/first_amendment

The key word is "congress" which can be broadly interpreted to mean the government, but not private corporations or individuals.

Free Speech != The First Amendment

The First Amendment is just a law which prevents the US government from restricting Free Speech. Free Speech itself is a principle which can be applied anywhere.

You're absolutely right, I didn't mean to imply that Reddit is in any way bound by the First Amendment. I meant to say that with free speech, you get the good, the bad, and the ugly.