How do you fix an infected machine? You need to download something from the internet.
Last infection I had, I did enough research online to figure out that I needed to download HitMan Pro. The infection before that, I needed Malwarebytes. My McAfee and Ad-Aware installations couldn't find or fix either of these problems.
I'm pretty tech savvy. When your non-savvy user loses his internet access because he has an infected machine, who is going to help him? The ISP? Surely, you're not serious. Their AV company? Useless if their software doesn't find the problem. Microsoft? Laughable.
What you'll end up with is lawsuits by the score and ISPs backing down with time and money wasted.