The difference is that (in theory at least) there's no discrimination for or against specific music streaming services. This is unlike the zero-rating described in the article, where specific social networks (and one specific encyclopedia) are unfairly prioritized over others.

If AT&T were to, say, exempt all social networking sites or all encyclopedic wikis or something to that effect, then I wouldn't be nearly as opposed to it.

Granted, as a happy T-Mobile customer who has put the free music streaming to good use, I'm probably biased in favor of that variety of selective discounting. However, I'd be opposed to it if, say, only Pandora was allowed or only Amazon Prime Music was allowed or somesuch.