The only way to detoxify the internet, is to get rid of the "social" aspect. Starting with gasp comments. My online experience has been that much better, since adding comment blockers to my browser.
Reddit has a large user base and a myriad of subreddits where different solutions have been tried. So far, the best I've seen is strong moderation: clear rules and swift enforcement. AskScience is a shining example of a high quality subreddit, although the comment section usually looks like a graveyard with 90% of the comments removed.
But then somehow a few "bad guys" get to become moderators and everything goes back to s*it. As someone has said above, it's all about the incentives. No-one has enough reasons or available resources to want to take over an obscure sub-reddit with almost no real-world influence, but when there are State actors involved you can be sure that things will turn sour. My most recent such experience is with /r/syriancivilwar, which used to be decent enough two or three years ago (even if some of the posters had actual ISIS flares), but since the troups-on-the-ground involvement of both Russia and Turkey the sub-reddit has become an echo chamber for those interests.