Not really. Third party code that you haven't installed does not run in an operating system at the click of a button. It does in the browser. By the logic you'

Not really. Third party code that you haven't installed does not run in an operating system at the click of a button. It does in the browser. By the logic you're outlining there's no reason to sandbox a browser at all, since it's no different to an operating system. Experience suggests that would not be wise.