[1] Could be that the website owner polices their site effectively, or maybe they grease enough palms to keep their site. The reason doesn't matter. The point is, there are other possible outcomes.
None of which are good. Either the site is taken down, an onerous burden is placed on the site owner to do the copyright owners' job of policing content, or yet another arbitrarily enforced law sits on the books, waiting for some enterprising media exec or prosecutor to contort it around their case of the day.
The content producers need to make lawful content delivery a better experience than pirating things. I love steam because it makes things much easier to download, install and keep up to date. It's a better experience all around.
I am all for taking down websites that are gross offenders but this legislation is like cutting off your foot because you stubbed your toe.
Without SOPA: Let's pretend that there is an innovative site that is going to be made in a few years that allows people to submit things to it and sell. This site gives some creative person a chance to make a full living. (this is actually happening now in many places)
With SOPA: Two options: Site either does not get created at all because of fear of creating sites that might cross SOPA at some point or this site gets taken fully off the internet because some other user on it posted some sort of infringing material for an indefinite period of time. in either case the creative person is out of luck with respect to making a living from their creative work.