In the old web, most content never changes. The only exceptions seem to be traditional news outlets (CNN, New York Times, and so on). That means search engines can crawl most sites infrequently and nobody really notices. Missing the last few days worth of stuff isn't that big a deal as long as you crawl those "news" sites regularly. Also, there's no way to find out which pages have changed without crawling the whole site, and that's quite expensive.
In the new world, feeds update frequently. Blogs start to look a like like "news" sites to search engine crawlers. But the updates are contained within the feed, so there's no need to crawl every link on the site looking for the new stuff. In other words, the cost of staying current on site changes is much lower when feeds are available.
Jeremy's post could just as easily be labeled "dynamic" vs. "static". He also references a blog post by Joseph Scott lamenting the current state of feed search which I commented on -- I tend to use PubSub to keep track of what people are saying about us. Of course, I set up the subscription too late (1 day! It's amazing how fast we are moving these days) to capture some nice things that people have been saying.
Keep thinking about how to add dynamic content that is useful to your community. Dynamic, updated, relevant content keeps people coming back. And of course we have a few tricks up our sleeve to help you do this, which will tie into both feed searches and web searches.
And if your current community or personal publishing platform doesn't do dynamic content…well, perhaps it's time to start looking for a new system.