Sites without aggressive SEO and ad placement may as well not exist as far as the Googles of the world are concerned.

This allows for surfing and exploring the web in a non-structured way. If you're not explicitly searching for a site or a site doesn't comes up in a feed you subscribe to, then you'll never discover any of this stuff. Web rings help to decentralize the web and make it more discoverable again.

Discoverability, I suppose.

At least one human has voted that this page is worth spending the time to do the data entry task to get it to show up.

The early internet yes, the modern internet encompasses everyone and everything, it's a victim of its own success from the geek perspective.