Over here, first, in this corner, we’ve got usability guru Jakob Nielsen. Nielsen is telling us that smart people will forget about blogging and write articles. Blogs, says Nielsen, are a dime a dozen. If you want to “demonstrate world-class expertise,” write long, in-depth articles that you can get people to pay for.

“Blog postings,” says Nielsen, “will always be commodity content: there’s a limit to the value you can provide with a short comment on somebody else’s comments.” Note how the definition has shifted without notice: all blog posts have somehow become “short comments on somebody else’s comments.”

As the article continues, Nielsen explains that his advice is aimed at the person who wants to establish that he is the number-one expert among the thousand bloggers in a field. This quantitative focus is awfully crude: among 1000 specialists, who’s to say there is a “number one”? By what measure? You’re going to find a whole range of sub-specialists and eccentrics, deep-niche experts and synthesizing generalists. But Nielsen’s analysis is built around this sort of comparative ranking. He maintains that, since blog posts are so variable in quality, a blog will never do a good job of showcasing your expertise. If you want to be top dog, make sure your barks are long and full of detailed research.

But Nielsen’s tract isn’t actually about how to become a “world-class expert” or even how to broadcast one’s world-class-expert-hood. It’s about the most efficient way to get people to pay for your content. Nielsen starts from the assumption that your goal isn’t self-expression or persuasion or enjoyment or anything besides customer acquisition. People won’t pay for blogs; therefore, blogging is a waste of time.

But no blogger I’ve ever heard of has actually tried to charge for content (tip jars are the closest anyone’s come). No one seems to want to do so; it runs counter to blogging’s DNA. Long, in-depth articles are a wonderful thing; who would dismiss their value? But Nielsen blithely dismisses the value in 999 out of a thousand blogs. He doesn’t seem to understand that, most of the time, that value is created not in hope of finding paying customers but, simply, for love.

Now then: here, in the other corner, we have Marc Andreessen. He’s the guy who whipped up the first popular Web browser for personal computers. In 2003 he rashly dissed the need for blogging, saying, “I have a day job. I don’t have the time or ego need.”

But he’s come around, and in the past few weeks he’s poured a huge amount of thought and energy into an impressive new blog. Yesterday, in a post titled “Eleven lessons learned about blogging, so far,” Andreessen wrote, “It is crystal clear to me now that at least in industries where lots of people are online, blogging is the single best way to communicate and interact”:

Writing a blog is way easier than writing a magazine article, a published paper, or a book — but provides many of the same benefits.

I think it’s an application of the 80/20 rule — for 20% of the effort (writing a blog post but not editing and refining it the quality level required of a magazine article, a published paper, or a book), you get 80% of the benefit (your thoughts are made available to interested people very broadly).

Arguably blogging is better because the distribution of a blog can be even broader than a magazine article, a published paper, or a book, at least in cases where the article/paper/book is restricted by a publisher to a limited readership base.

Andreessen obviously isn’t writing his blog with any intent to try to charge people for it (as one of the founders of Netscape he presumably doesn’t need that kind of change). I doubt, either, that he is blogging in order to be known as the one-in-a-thousand expert on anything. So Nielsen would tell him, don’t bother — don’t waste your time.

Andreessen doesn’t look likely to heed such counsel. Certainly, as a tech-industry celebrity, he’s had it relatively easy in attracting attention and readers. But he’s hardly coasting. His posts, in fact, look suspiciously like the long, in-depth articles Nielsen advocates; they just happen to be posted in blog form.

From what I can tell, Andreessen is blogging because he finds it fun. Because it connects him to a wider group of people who share his interests. Because it gives him a chance to think out loud and tell war stories and give advice. And because, having started, he can’t stop writing (long, in-depth) posts.

It looks a lot like love.