What about looking at this from the perspective of the site owner? Facebook comments can do more for the site owners than the alternate comment systems. Increased exposure through facebook news feeds should help introduce their sites to new people.
Just as important is the back-channel that allows comments to be created and shown in different places (this was mentioned as an "incidental" note in Tech Crunch's article describing the comments system http://techcrunch.com/2011/03/01/facebook-rolls-out-overhaul...). I find it particularly appropriate to bring this up here on HN because I expect Tech Crunch to look with envy or exasperation when comments are posted HERE (HN) about stories appearing THERE (TC). Why shouldn't TC want to have all of the relevant, useful comments appear next to the content they create and host? Facebook comments could help that happen (indeed, so could have disqus if it were used by HN and TC both. Alas, disqus, RIP).
Just as important is the back-channel that allows comments to be created and shown in different places (this was mentioned as an "incidental" note in Tech Crunch's article describing the comments system http://techcrunch.com/2011/03/01/facebook-rolls-out-overhaul...). I find it particularly appropriate to bring this up here on HN because I expect Tech Crunch to look with envy or exasperation when comments are posted HERE (HN) about stories appearing THERE (TC). Why shouldn't TC want to have all of the relevant, useful comments appear next to the content they create and host? Facebook comments could help that happen (indeed, so could have disqus if it were used by HN and TC both. Alas, disqus, RIP).