Unlike smart phone hacks or other mostly-theoretical vulnerabilities, PCs are constantly hijacked by drive-by-downloads that exploit browser flaws.

FORBES: Google's Chrome Leaves Another Hackathon Unscathed

Sites that exploit browser security holes to install software (such as malware, spyware, viruses, adware and Trojan horses) are in violation of our quality guidelines and may be removed from Google's index.

FORBES: Magazine Article

And that really limits what kind of damage a browser exploit can do.

FORBES: The Web's Edge