I think there are two fundamentally different kinds of dialogue on the internet.
1. Dialogue in communities directed towards a purpose.
2. Dialogue in public forums.
In my mind, the only place where filtering should take place is in #1. If you want to see information about specific kinds of basket-weaving, then the communities directed towards basket-weaving should give you the tools you need to see that information, and should police their communities such that there isn't too much non-basket-weaving content. But in public forums, I think that people should actively resist filters. I see filters as a case of trying to make something straight out of the crooked timber of humanity. Not only is it a goal that may be fundamentally impossible, it has negative impacts on the people who use the filters. To the well-filtered person, the general public may look more civilized and reasonable than they actually are. This can manifest itself, for example, as the well filtered people being baffled by the success of populists candidates because "everyone I talked to online could see right through them!"
I think online communities would be better off ahead of time if they made an explicit choice about which type of dialogue they were hosting, and communicated that choice to all visitors.
I think the apparent "rise" of trolls is mostly borne from sites with a disconnect between their stated goals and their actual rules. News organizations are likely to say they want free-speech forum in their comment section, but people mostly expect conversation directed towards the topics being reported on. Reddit was formerly a free-speech platform, but subreddits started behaving more like directed-communities, and the admins encouraged this site-wide. Hacker News is clearly a directed community, and so has fewer trolls, while 4chan is clearly a free-speech community and therefore ALSO has fewer trolls (i.e. most people on 4chan conform to 4chan norms, even if that would be considered trolling elsewhere.)