In the past the strategy was selling albums to tempt people to come to their concerts, now is vice versa.
In these days is not problem to download any music you want (mostly in mp3).
So now the strategy is performing live music to be recognised as a talent/real artist/genius (however) and be wanted so much that people will support you and will be willing to listen to your music in better quality comparable to CDs.
That means that streaming music here is still a good way to propagate and how to show your art in full spectrum instead of sh*tty samples.
If you want to show what are you capable of you don't sell it first, right ?