How can you possibly compare HN, reddit and Grooveshark? The first 2 aggregate
links to content, Grooveshark distributes content (often unlicensed). That's akin to comparing IMDB and iTunes, because both have movie related content? It's nonsensical.
If you want to use reddit as an example we'd have to pretend that reddit downloads the content from any submitted link and serves it, so let's pretend that happens: if a company went to reddit and said please stop downloading our website content when it's submitted from the domain website.com, would you do that? Would you tell them to fuck off? While profiting from that content?
Grooveshark could if they wanted without any effort comply with what companies like Universal want. They choose not to. It's not about whether or not they comply with the law. It's absolutely not unreasonable for any artist to expect their music not to be on Grooveshark, Grooveshark made a business decision to use the DMCA to their advantage.
> They aren't supporting Rihanna, and I'm fairly certain that they don't have to.
That's fine, they don't have to support Rihanna, but what they should not then do is take her content anyway. If they're not willing to comply with the wishes/expectations of the rights holder (which probably isn't Rihanna but let's pretend it is for simplicities sake) then they SHOULD NOT be making money from that content!
Grooveshark is a business that takes other peoples content WITHOUT PERMISSION and then makes money from that content and uses the DMCA to get away with it, doing the bare minimum to be compliant. How can anyone defend that?