The ShareAlike term does only kick in if you make a derivative work. But if you’re distributing verbatim, it isn’t relevant — you’re distributing under the terms of the license granted.

The “exploitation” that SA does not prevent is twofold:

* Inclusion of a SA work into a collective work (e.g., verbatim track on an album) does not force the entire collective to be licensed under SA.

* SA (without NC) works can be used for commercial advantage without getting permission from the copyright holder.

I think NC does have a big role (e.g., for those who already have a business selling verbatim copies, and the merely envious :-)) but is overused. Most people aren’t going to make money selling verbatim copies anyway and preventing commercial use just suppresses potential use, which generates demand for appearances, services, fan items, patronage, etc.