Do you have an issue discussing topics from blogs?
If the author is blogging about actual news stories which can be backed up with other links if the reader feels like looking for them, why would anyone have a problem posting, discussing, debating or forming their own opinions?
I post things from many places- places I visit every day. Some are blogs, some are news sites and some are archives. Why would the site I copy and paste from matter if the topic can be corroborated?