Don’t sell yourself short. You’re absolutely right that this sort of action can be very detrimental to a business. It’s largely childish even if it feels good.
I’ve also learned (through the experiences of others) to always get paid up front for political work. Bummer that you got stiffed. I’ve gotten stiffed once for about $1300 of work and I really could have used that money at the time. Funny thing was their lawyer came to me for help when they were re-organizing their business. I brought up the unpaid invoices and never heard from them again.
As far as your questions around how much creative control they had and how much they were just hired as technicians. It depends. Things could have swung really hard in either direction. Impossible to tell without more information.
