From my experience remediating machines at a university support shop, we see far more that have crap addons installed that hijack search and inject intrusive ad

From my experience remediating machines at a university support shop, we see far more that have crap addons installed that hijack search and inject intrusive ads into every site. They're never installed through the Chrome App Store, so I'm guessing Google is trying to combat things like this where the end user installs a coupon finding program and their browser gets taken over as a result.