I think there is a bit of cognitive dissonance in the tech community about "disruption" versus "big companies." Technology, in general, makes it easier to scale companies to large sizes, and "disruption" often involves using technology to enter an existing industry that is dominated by small, inefficient companies. A great example is Uber. Uber is making the taxi market a lot more efficient, but it's also well on the…
Yes, iTunes changed the music industry, but who got killed? CD retailers, primarily. The bulk of music sold through iTunes is still licensed from big labels. Spotify licenses music from the big labels. Ads, TV shows, and movies license music from big labels. Heck even the most popular videos on YouTube are almost all the official Vevo versions of big-label songs.
Piracy is harming album sales, but because big labels have so much financial leverage over new artists, they have simply started requiring "360" deals for a lot of new contracts, which give them a cut of all revenue streams: not just albums, but also tour revenues, merchandise, media appearances, sync licences (ads and movies), even publishing in some cases.