Earlier quoted context omitted.
The problem with downvoting (at least simple versions) is that it allows separate communities to interfere which each others' communications. So, say you have hunters and animal-rights activists. They should be able to talk among themselves on Google+, Twitter, or Facebook without interference from the other side. You don't want one side to start downvoting the other side's posts into oblivion so they can't even talk…
A lot of people believe it's their right to disrupt the communities of others. They call it "activism" or "advocacy" or "defending family values" or whatever the justification du jour is. It's all basically trying to stake a claim to the whole service as the territory of your tribe. I like the idea of reinforcing some separation, but I also fear it may be too late. A lot of people seem to derive joy from attacking th…
Take for example, a forum on ISIS. Yes, I've just triggered Godwin's law. I'm sorry about that.
Now, the idea is that there should be no challenge to ISIS on some parts of the Internet because they have the same right as anyone else.
However, this fails Karl Popper's criteria, don't tolerate the intolerant.
I support the criticism of any prejudiced and intolerant group in any forum (even the ones that Political Correctness blindly defends). If the goal of a group is truly noble, I will often support it.