I think it's just the vocal minority here voicing their opinion. Franze you mention all great points with data to back it up (I've noticed the same fwiw).
WRT to SEO, anonymity, posting on your feed and notifications.. FB comments are crawlable, You can still remain anonymous with FB comments (sign-in with a yahoo account, etc.) and you can skip posting it on your feed and I've been notified everytime someone has liked/replied to a comment I've made using Facebook comments. More so than Wordpress, who wants to subscribe to a popular author and constantly get notifications throughout the day whenever anyone makes a comment??
WRT to SEO, anonymity, posting on your feed and notifications.. FB comments are crawlable, You can still remain anonymous with FB comments (sign-in with a yahoo account, etc.) and you can skip posting it on your feed and I've been notified everytime someone has liked/replied to a comment I've made using Facebook comments. More so than Wordpress, who wants to subscribe to a popular author and constantly get notifications throughout the day whenever anyone makes a comment??