The websites I frequent are not reliant on ad-revenue, and those that are are easily replaced with ad-free alternatives that have existed for years, if not decades.
You visit Slashdot (obviously) and you mention Facebook and Google. There are three sites right there that *are* reliant on ad revenue, so you might want to rethink the above statement. And two of those three rely on IP for geolocation. It's not the most precise way to do it, but it works.