system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are these blackouts going to do to prevent SOPA/PIPA/OPEN/etc?

I get they're a means of protest, but what would it do to change Congress' mind on the matter? I bet you not 5 members of Congress are regulars here on Reddit. I can see Google perhaps having some affect, but not much. What needs to be blacked out are sites that Congress members frequent daily or need for work.
gpt
They will make people know something is happening and that people are upset about the legislation. People who may not be aware of SOPA and PIPA will notice that wikipedia and other large sites are down and will see why.  That should raise the profile of the issue and hopefully make more people aware its a bad idea, that in turn might put pressure on congress and the US government as a whole.