What is really the purpose of streaming??

I’m pretty sure there’s lots of classic rock on the streaming services that you haven’t heard, OP, and there’s a lot of music being made today that’s really good, that a classic rock lover would enjoy. Tidal let’s you stream free for 30 days sometimes longer. What have you got to lose? And if you already knew you didn’t want to try streaming, no matter what, why ask the question?

I asked because i was not sure what it was all about. 

OK. Enjoy those same old cds!

What I like about streaming is as many here have mentioned, the access to literally millions of albums. I like to read through the music forum here and get ideas for new music. For example, one band that seems  popular from the classic rock era, tattoedtrackman, is Camel. I'm not really familiar with them yet I have access to their music and can listen to different albums without having to purchase them. This is a great way to explore new music options conveniently at my fingertips.

I'm not sure what the OP means by "purpose" of streaming, but one obvious advantage of streaming is that it gives younger music fans immediate access to vast amounts of music that would have otherwise taken them large amounts of money and years of time to accumulate.  Back in the 60s I would have loved to have had a multi thousand album collection of rock and pop records for $10.  WOW!