So SoundCloud users had a good run, but now the popularity of the service reached critical mass and raised the ire of the labels so they're knuckling under like every other provider. SoundCloud (sensibly) doesn't want the burden of dealing with the massive copyright infringement by it's users and outsources the job to the owners of the tracks.
Now I get that it sucks that you don't get explicit explanations of what infringed, and I worry hugely about their power to supress content that they actually do not own, but:
1. Stop pretending that you should get a free ride because you're promoting the artist. If you actually give a shit, discover and promote new music from awesome bands that are not beholden to the labels. That's the only way to break the stranglehold.
2. Don't rage at the service that provides a great product to producers of real, original content, just because you've repurposed the platform to promote your infringing mix.