Sorry to hear this has been your experience Adam. And everyone else that feels they have no choice but to concede due to clients threats. I get it, we all have to eat and pay the bills.
Sadly this is becoming a trend because it has been allowed for too long to become one. Too many artists have "given up" and therefore the unwritten policy of those in powerful positions with a greedy appetite has simply been accepted as absolute rule by a lot of workers.
It does boil down to each persons experience. Some have allowed themselves to be abused for the sake of survival, and others have fought in the name of that very same survival.
For myself, I have stood my ground the best I can. Some wins some losses. I've declined work before while actively working at a studio due to the nature of it's content. I respectfully terminated a contract three days early because of it. Offering the lost days cost back to the client so they could find a replacement for that particular project. It was the only respectable thing to do since I terminated the work and not them. I've been booked by them multiple times since. I've lost clients and have gained more. There will always be somebody in need of something. I've chosen to stick with the respectable ones.
My feelings are that if you (to any client) believe abuse and disrespect of the skill and talents required, are trivial and that anyone can do it nowadays because of computers. Then by all means find someone else that is willing to take the abuse, stress, health implications, and risks of non payment.
Those client mindsets will always exist, but that doesn't mean you shouldn't stand your ground and respect yourself and the hard work you do that ultimately makes the client a hell of a lot more money than you'll get out of it.
The advances of technology certainly have made access to post-production tools easier, but not the education of the user nor proficiency in using said tools better. If the human is just clicking buttons and not thinking of the big picture, it fails. Every time.
I know it will not change things simply by saying all this, but I'd hope that more artists flooding into this industry (at a ridiculous rate) will at least think about doing better for themselves by doing better for the industry as a whole.