That said, I think the answer to your puzzlement is pretty simple: every situation is different.
For example, I don't much sympathize with taxi medallion monopolies. While I understand how they evolved, today it's clear that the existing taxi business model needed to be disrupted in order to improve the consumer experience. But that disruption has happened because of companies essentially violating existing regulations on taxi services.
On the other hand, I look at a business like GS, which generated its revenues by selling subscriptions to a service that dispensed content it did not produce, without compensating artists for the privilege, and I see nothing more than free riding on the backs of people who did the work to produce that content.
Of course, there's an ironic counterpoint here: were it not for the Groovesharks of the world, it's possible demand would never have been generated that now supports legal alternatives (in the same way that I'd claim music piracy is one of the reasons the iPod was ever brought to market).
Tricky. :)