When you practice shooting a basketball by yourself, there is a degree of separation from an actual game of basketball. With no defender to pressure you or fight for a rebound, what game is there?
Bump it up to a one on one game. Now we have an adversary, someone to fight for rebounds, dribble and shoot around, and steal the ball from. Again there is still a degree of separation: no teammates to pass to or opposing players to cover and or avoid.
Bump it up again and again and there are still degrees that separate you from a real game of basketball; whether that be playing half court instead of full court or 3 0n 3 instead of 5 on 5.
What is interesting about basketball is that, past playing by yourself and maybe one on one, the degrees of separation only matter so much. Not all of us care to play professionally. Does it matter whether we play 5 0n 5 on a regulation size court? The athletic and communal bond of the sport can still be felt in a pick up game.
Past playing music by yourself without anyone listening or playing along, the degrees of separation from performance only matter so much. Like basketball, not all of us want to make a career out of music. Does it matter whether we play Carnegie Hall for an hour long recital or are going on an East Coast tour? The artistic and communal bond of music can still be felt in a small town garage jam session.
That is the thing we do not want to separate ourselves from.