Was Napster knowingly criminal? By most accounts yes.

How about Uber? In most cities they were by allowing airport pickups?

How about Amazon? Remember when they aided and abetted customers with sales tax evasion for years?

Napster was knowingly criminal. Source: I was there.

During discovery they found emails from Parker saying, "Of course it's illegal. We know it, they know it, we're going to be the biggest thing in the world anyways".

If this is no big deal, then there would be no need to dance around it, right?

But I would not conflate sharing a music file with hiring a hit-man.

Those are almost entirely civil issues so not really.

If you look at how Napster changed the movie and music industry it just makes more sense for the government to make an example of the Napster of drugs.