I think the idea is that the ad networks then don't have any idea what you are actually interested in. The problem from Google's side is that it is pay per click for the advertiser so advertisers are paying for these fake clicks.
Google will ban a site from hosting Adsense ads if Google believes that the site's operators are generating fake clicks. The way they detect this is a trade secret, but many sites have gotten arbitrarily banned after users seemingly clicked ads artificially in a misguided attempt to help the site.
This extension will no doubt be used by a certain subset of users. Those same users may use some sites in a disproportionate number, that could result in people's favorite sites getting banned and losing the ad revenue that keeps the lights on.
I don't actually think this extension is "bad" or "wrong" just might have unintended side effects.
If you object to ads, is that a bad thing?