>>"Google does pretty much the same thing, it links to copyrighted material left and right."
Well, it has links to all kinds of things, but links to copyrighted material aren't its main business and it wouldn't obviously be worse off without them, nor, as far as I know, does it go out of its way to acquire those links.
To the extent that there are similarities, there are also significant differences, and it would be faulty logic to say that simply because both sites have links on, they must legally be precisely equal.
It's a bit like the situation where someone runs a car boot sale where some dodgy stuff is sold, even if they're not doing the selling.
At one end of the spectrum, someone can't easily police every single item for sale, but there does come a point where the proportion of dodgy goods is so high that the operator was substantially and knowingly profiting from their sale to an extent where their behaviour was definitely less moral, and possibly less legal than that of an average sale organiser.
Even if where that point is or (should be) might be a matter of opinion, it's not viable to pretend that 'similarity' =='no difference'.