Blogging used by Gurus? Hmmmm...

A few days ago I was watching Brendon Burchard's free 4 hour webcast he gave which was pretty cool. One of the things that he mentioned during the webcast was that you should have a product first or have one planed out before thinking about opening up a blog or any other marketing platform so you know what audience to attract. After hearing that, my thoughts ran off with themselves and began thinking about, "do even most 'gurus' even keep an up to date blog?"

So I did a little research and to my surprise I noticed a pattern occurring that most DO NOT! I mean, if most of you agree with me that we've been taught it's good to open up a blog to gain an audience and to get free traffic to help build your list etc. I looked at people like Eben Pagan, Frank Kern, Amish Shah, Andy Jenkins, Ryan Deiss, and even Brendon Burchard...So my question is whats up? Am I missing something here? Are what most of these "gurus" are doing is just having huge product launches every year where they build a huge affiliate army and launch their products?

For instance, I noticed the pattern with Eben Pagan, every year around mid spring he'll announce he'll be releasing a product in May or June, prior to that he'll release FREE video content where he'll teach some valuable things up until the day of the launch. Once he launches the product, you don't hear from him for the rest of the year, no keeping up to date with a "blog" and/or new videos unless you count the countless affiliate offers he offers throughout the year through his list. So I guess my question is, is this a proper business model to follow for online? Is even having a blog even worth the time and headache if the only thing you have to do is build a product that people need and get several JV partners to help you promote your product? What's your thoughts on this?

P.S. Not only that,but wasn't it Frank Kern in his State of the Internet address that said, "...Product Launches are a bonus, and not a business model..." and I'm paraphrasing.