Most bloggers have no institutional credibility, and so they must build it, by linking transparently, and allowing you to easily double check their work. But more than anything, because linking sources is such an easy thing to do, and the motivations for avoiding links are so dubious, I've detected myself using a new rule of thumb: if you don't link to primary sources, I just don't trust you.
When it comes down to it, @Taskrabbit is about neighbors connecting with neighbors