For those who use Disgus, this set up is probably costing you visitors to your blog and comments. People generally aren't going to join Disgus in order to leave you a comment, and most people also aren't going to sign in through facebook etc. to do so. If you have an option to change your settings you would be doing yourself a favor. Recently involved in several blog challenges this problem has popped up, and there's been much discussion about it, the comment I've seen most is people are avoiding blogs like this, so you're costing yourself blog traffic. It's very difficult to leave a comment.
AND
Those using google+ are also an issue.
*Many of you may not be aware and wonder
why folks aren't returning your visits and comments. Google+ has a
setting now that does not allow others to comment, in some cases your
blog isn't even visible unless people register with google+. You are
losing people without knowing why, as many of you don't have means of
contact...people aren't able to let you know. I've been able to alert several, who did not know of the problem
and change in settings; some have been able to fix the problem. If
you're one who's fixed the problem, please leave the instructions on the
fix so that we can pass along the information to help others. Please
leave it here the comments and or email me directly at sandycrochet at
gmail.com* It's my understanding it has to do with a default setting that has recently been changed by google+.
This is what folks see when they're not able to leave a comment. If you click on this it requires you to join google+.
Additionally, it would be best to facilitate return visits and comments if you did not use your google+ profile page, people have to go searching for your blog and click a 2nd or third time to get to you. Please use the drop down box and add name and url of your actual blog vs your google+ page, and or use hypertext in your comment to direct to your blog, not your profile page.