Robert_Charlton - 7:26 am on Nov 2, 2013 (gmt 0)
Facebook does let you use their commenting system on your own site.
I just commented on a major newspaper site that was using Facebook comments... and I found that the comment was prominently featured, along with the original newspaper story, on my timeline on Facebook. I didn't see whether it appeared in my news feed.
Whichever... depending on your FB following, this might be a much more powerful way to share a comment and reach out than a comment on a site's native comment system could accomplish by itself. (I should add that I found the newspaper story via Twitter search.)
The tradeoff with the FB commenting system, as I understand it, is that the content is on your Facebook page, not on the article that's on your site. I'm wondering whether... for Google... this is as effective as a native commenting system that would be leaving the comments on your site. Essentially, I'm assuming, you get more outreach with the FB comments, but less direct search benefit... though the comments are there on your site for your site visitors to read.
There's also the question about whether the direct search benefit from user comments is as meaningful as the outreach and diversification of the comments on FB.
Yes, it is way complicated.