Peter, you are absolutely right that the issue is whether SOPA is the right response. Just to clarify on the web hosting site comment. The existing law does require the web hosting site to take down copyright violating material if provided with a DMCA takedown request. Well, require isn’t exactly the correct term. But there is no actual penalty or recourse if they don’t that is PRACTICAL.
The responsibility to police falls on the copyright holder, and if you’ve been infringed by 1,000 entities (and some websites have been), you have to send 1,000 DMCA’s and you may or may not succeed, because right now, there’s no real penalties for the webhosts, or Facebook, YouTube if they do not act.
Even with DMCA what happens is that typically even if one succeeds in getting ONE stolen article, song, removed, the infringing company simply adds another one. It’s the webhosts, Facebook, YouTube that enable theft and there are people who know that and scrape entire websites to make a profit, using other people’s efforts.