But not necessarily. Some musicians exclusively learn to play through being taught and jamming with others. I admit it's rare, and even as an extrovert it's not true for myself.
However, for a more damning condemnation of this "creativity requires solitude" viewpoint, we only need to venture into the world of improv theatre. Almost everyone in improv is unleashing non-stop creativity, but they've almost never practiced improv alone. It's the total counterpoint to this unnecessary association between artistry and isolation.
Highly extroverted artists exist. They rarely create alone. They rarely practice alone. I urge people to acknowledge that this is a worthy way to be a compelling artist, rather than acting like the preference of the introverted artist is the only worthy way of doing things.