That only works if you form a team with the artist. It doesn't work when the person you're commissioning free stuff from is an external artist who is getting flooded by both paid and unpaid requests. Even a token amount will let them know to prioritize you over the freeloaders.
This is true. I have paid friends free market rates for work; even though they would have done it for free.
It’s a matter of Respect. It’s really amazing, how treating folks with simple Respect can change everything.
I like working in teams, but I also participate in an organization, where we’re all expected to roll up our sleeves, and pitch in; often in an ad hoc fashion.