A few things happen here.
1) Technology changes. I used to have another company, and as part of that company website, I had a bunch of animal-related articles. I wanted to update the site because the code was very 7 years ago, and figured I would put it into a CMS for safe keeping. I realized that a whole lot of people linked to those articles, so just to be nice ... I put forwarders where all of the original URLs would be to tell you where these things were now.
However, keeping the old articles works great for this pet-related thing, because that information hasn`t changed in a long time. Should you be reading the same SEO articles that you read now in 5, 10, 20 years? Probably not. So there`s a good reason why topics like article marketing should disappear at some point.
2) People run out of money. In that above site, I can keep it going because basically I have a bulk hosting purchase - so one small site really costs me nothing. If I was paying for a site long after it had become useless to me, especially if it was high bandwidth, I might have dropped it.
3) People go on to do other things. There was a place called "Bullwinkle`s" a few blocks from my grandma`s house when I was a kid - you know, like the Bullwinkle and Rocky show? They had video games and pizza, and a stage where you ate that had live character shows and a water fountain thing that danced. (Like the Mentos stunts, only with water, coordinated to music.) I would have loved to take my kid there now, because I loved going there when I was a kid ... but it`s just not there. It`s a dance club that is definitely not for kids. The Olsen`s cherry orchard across the street? It`s a brand new huge Kaiser facility. The race track up the peninsula where they used to have stuff for kids on the track center? They are talking about tearing it down to put up condos. The point is this: things change, and people go on to do other things. It`s unrealistic to expect information to stay in one place forever. As I have now been using the internet for over a decade, the stuff I once knew is gone, replaced by new and different things. Try to not think of it as a fad, but maybe a career or market correction ... they stopped doing that which they either shouldn`t have been doing in the first place, or that which they decided they couldn`t excel at.
4) Businesses die. This happens more often than not ... if you are a small business and you`ve been making it for a few years, congrats! You are in the minority. A lot of them just disappear.
5) Businesses change. To be stale is to be dead in the business world. So when they go to redesign something, sometimes a few things end up misplaced or lost forever, especially when you have a really large site with a lot of content. That`s why there`s a search button!
And to answer Craig, the reason why I use a blog/CMS is so you can find things. If I put them in flat files, or whitepapers, or whatever else ... you`re never going to find that information. I guess then a bad link on Google isn`t an issue though, if you could never find it in the first place!
So, yeah. It`s not a "blog", it`s a "CMS". And what you do with it is your own deal - just try not to stink up the neighborhood with your useless ramblings.