The MP3 was a cool solo I recorded that my friend wanted to bring to her singing coach, but it could have been anything. An MP3 from some random CD that's never been available on the itunes, or maybe just one she wasn't interested in buying even if it were available. What you choose to listen to on your devices isn't any of Apple's business.
Streaming isn't a solution for getting media on a device either. It's a nice convenience in a lot cases, but because you're dependent on someone else to make the content available, and someone else to carry it, streaming is always uncertain and you should never assume it'll be available to you even when it has been in the past. As much as I love streaming media, it can't beat having a DRM free local copy you can keep, copy, convert, etc.
The point though is that getting an MP3 on a popular cell phone at any point over the last 3 years shouldn't be complicated. It shouldn't involve logging into accounts, needing to install bloated and intrusive software (itunes installed a service to always run in the background and set itself to start every time the OS was started) or syncing entire musical libraries (and god knows what else) anywhere. It should have been a drag and drop operation, but the internet is full of horror stories about people losing their music collections, collections being merged with other people's libraries, and requests for itunes alternatives just so people can get media onto their expensive devices.
I'm sure if she only ever used an apple computer with apple's itunes software always running on it, and no one else but her ever used it, and she paid for every piece of media she ever put on her device by using the itunes store everything would have worked wonderfully, but any deviation from that very narrow 100% apple-everything set up turns even the simplest things (like putting an MP3 on a cell phone) into an ordeal with 100% unnecessary apple-imposed complications and roadblocks.
The fact that it would have actually been easier (and probably faster) for me to install and setup a web server to host the file so that she (if she had the right browser) could download it to her phone really shows how fucked up the entire process is.