The problem with this view is that one person's hateful opinion is another person's oppressed minority opinion. There aren't many objective truths, moderators just end up enforcing their own world view (which we've already seen Facebook do).
If the internet is meant to be a platform on which people can express themselves freely (and I believe it is) then unsubstantiated and hateful opinions are a given, not a sign that the internet has failed, but that it's succeeded.
What failed is the naive, idealist expectation that the internet would raise the level of intellectual and cultural awareness of the planet, but I don't think many people really believed in that to begin with.
It depends on how exactly you define 'improvement'. Millions of people, speaking freely to each other, finding new friends sharing common interests would disagree with you.
The improvement I was talking about was the hope that the increased access to online communication would engage more people in constructive public discourse, include the voices of minorities and bring people with different backgrounds to a greater understanding of each other. Platforms like Facebook have utterly failed at that.
I don't think it is fair to consider large-scale censorship as the only other alternative. Having some kind of neutral editorial process to filter out the unsubstantiated, hateful opinions and leave room for a more nuanced discussion raises the level of discourse, and is the model that have been offered by traditional media for a long time.