What is really the purpose of streaming??

Not all "streaming" works the same way.  Spotify (various resolutions, not yet high res, sometimes CD quality) and Tidal (higher resolution, usually CD quality or better, more limited catalog) are subscription "streaming" services.  They do not use physical CDs, of course.

Then there are local hard drive devices (network attached storage) for music storage.  Music files from NAS devices can be played using "streaming" hardware ("streamers").  Again, no physical CD media, but the files are stored locally on the NAS or similar devices.  

The latter approach is the one I use currently, and it allows one to avoid keeping track of physical media (CDs) while accessing all of the stored CD albums via tablet or phone touchscreen app.  VERY convenient, and in my system sounds at least as good as a CD player (i.e., physical media player).

More listening and a vast online catalog of hi res music.

Less time feeding a CD tray like on an assembly line.

CD players are almost all jittery anyway due to the servo motors...

Good comments by @goheelz regarding streaming thru a subscription service and also by way of a home server or drive.

Now I have a question for all those who subscribe to Tidal, Spotify, etc; what happens to the music in your library or playlists when you don't pay your monthly bill, or if you cancel the the service?
Since this type of streaming is interactive, do you lose all your saved tracks?

  streaming is no good is for DJ gigs. i always used to have LP setup and played proper compilation LP when wanted to take break back in the time when CD players were only extra luxury and expensive.

@lowrider57 The music on your library has nothing to do with a streaming service it's stored on your hard drive or NAS or whatever. If you stop the streaming service you would lose your favorites or playlists you put together on the service account. Your own music would be intact. I hope that makes sense.