[dragonwriter]

> Why does a browser need a revenue model?

Because development isn't free.

> Why can't a browser just be a piece of software that's "finished", with the occasional security patch?

Developing security patches for the dwindling user base such a browser would have isn't free, either.

But even if such a browser existed, the browsers people would actually be using would be the ones evolving with the things people want from the web.