It's not too difficult to remember a time when music had to be purchased and lectures only happened once. Recording was trivial to begin but laborious to maintain. Don't forget to turn those tapes over so you can use the other side, as space is precious! The same was true of buying music: with the right resources, you could certainly have bought every album in existence, but who wants to deal with all those discrete physical objects sitting around?
So now the audio is everywhere. Yes, internet connectivity is a limiting factor. Yes, the DRM can be both obtrusive and intrusive. I don't care anymore. I can download all the podcasts* I could ever want without having to walk through the door of some specialty store. I can turn the music on and never hear the same track more than once. The biggest limiting factor is now time. That, and a willingness to be advertised to.
*Isn't there a better term for these yet? The whole pod- prefix should have gone the way of cyber-, though I suppose that my-**, e-, and i- are enjoying pleasant undead lives in the vernacular.
**Would you believe that mySimon is still online?