My feeling is that Spotify couldn't care less about Anna's Archive. It's bad but doesn't hurt Spotify. Just like Steam, convenient distribution trumps piracy, always.

If you look at the plaintiffs, Spotify is number 8 on the list, where the rest are the usual suspects: major record labels and distributors. Seems like Spotify was dragged along because they are beholden to rights holders, and they have to show that they take this seriously, and do something about it.