Let's say I go to shop at Kmart, and every single time I go there, I go straight to the sporting goods section. If I do that, I don't want to get a Kmart flier about housewares. We're trying to market things that you've shown you're interested in. It's not because we're busybodies and want to find out about who you are. There's no question that online consumerism has enabled companies to cheaply find their niche and to increase efficiency.
Online marketing takes it to the next level.
A cataloger doesn't even know if you looked at his catalog or just threw it in the trash. That's a whole new thing. If they knew how long I looked at a page and if they knew what pages I looked at, they'd have a lot better idea of what my interests are. Businesses are unlikely to stop these practices. Chances are it's only going to become more pervasive.