Many bloggers will link to friends. And to A-listers. Few will post links to those they do not know or have not met at one time or another, even if the poster is in their geographic region and/or has similar blog content. There is not a huge care as to whether or not they are widely linked--then again, to many they do not even know that blogs can be used for business, or that blogs often contain and convey information about the tech world, or that blogs are considered to be a form of journalism. Most aren't even into tech, would never consider themselves tech people--many don't think much about the world of journalism either or that by publishing a blog that they are part of it. Often they link to A-listers because they are the first ones who come up in RSS. They have been around for a long time, and non A-listers feel a need to link to them, as if linking to an A-list blog will make them look as if they are in-the-know of what's hot in the blogosophere. Even if there's no reciprocal link. Many times, too, these bloggers really aren't interested in building communities outside of their pre-established friendships. The blog exists to communicate to their friends or just to get word out to their own insular little community.
Some bloggers might even like your blog, but updating the blogroll is often time-consuming...even trying to figure out blogrolling software is time consuming. All of this inhibits linking...
So much for Jeff Jarvis' theories on blogging being a meritocracy and the best blogs rising to the top. It really is like the biosphere--you get more if you literally know more people beyond your own little screen or if you are already very established.
And to get to know people, you meet them. With bloggers, that can be a tough thing to do. Leaving comments sometimes works...and sometimes doesn't. Email is also hit or miss. Alot depends on the personalities of individual bloggers or their email spam-blockers--neither of which being completely deducible from their blogs.
I'm also going to do a little more testing on this to see if I can be proved wrong.