I think a lot of people come here without understanding the difference between discussion, discourse and debate. To me, this site is mostly for discussion, that is, we talk about things in a fairly casual manner for the most part.

There is also a lot of discourse, which is generally speaking, talking to each other intelligently and earnestly about various articles and issues that concern us. For example, I would say that this thread invites discourse more specifically than discussion.

Debate is much more in line with taking a position, defending it, modifying it, exploring other angles with the intent of winning.

Personally, I am not looking for a site where I have to deal with people making comments such as "source?" or even to bother explaining myself. I do that at work all day. It's not what I want to do in my leisure time. What I do want to do is chat with other people who know about stuff I don't.

To finally answer your question, I don't think that hubski is an echo chamber. There are many documented instances of sharing information and the exploration of topics that interest individual users. Yes, there are also documented instances of users coming in, fists balled, looking to pick a fight over some ism or another or whatever the flavor of outrage is that day. From my experience, I don't think that we really need to worry about an "echo chamber" because hubski is not the kind of community where we generally look to reinforce any one particular point of view and certainly not with an intent to get others to think in that way.