Blogger is one of the more popular blog hosting services. I daily run across blogs who use their excellent software to host their writings. I also daily run into blogs using the system that have disabled commenting options for anyone but other users of blogger..
I hit at least 2 blogs a day where I am about to comment, but cannot because only blogger users are enabled. Seems pretty silly to me, I'm not really interested in opening a dummy blogger account and another set of emails & passwords added to the dozens I already have seeing I use other software to host my blog.. The blogger system requires random characters to post a comment, how only allowing 'blogger' users to comment limits spam is well beyond me, but I'm quite positive it limits comments because I keep hitting the brick wall at other people's blogs.