Unions protect workers from being exploited and abused. If you're not happy with how some employee performs, you can still fire him in place. But be ready to prove it. No more firing people on a whim just because.
If game industry isn't sustainable without exploitation, then we need it to adapt, and not the other way around.
How do you prove that an employee took two weeks to find a bug that should have taken one day to find?
How do you prove that writing a domain-specific language was a bad decision compared to defining a complex XML schema?
How do you prove that an engineer is bad at explaining technical concepts?
I do think employees need organization and culture to negotiate better in the short term and manage health and career in the long term. But I don't see evidence that either the employer or the union leadership have the right incentives to meet those needs.
Email archives of PIP goals and the like. But that doesn't even matter. All you really have to do is prove you didn't fire them because they asked for OT pay they were owed.
Yes a Union cant stop some one being fired if they are guilty of Gross misconduct but they can make sure people don't get fired for say accusing a manger for unwanted touching or to make wahy for the CEO's nephew.
For example I bet James Danmore had no advice before his internal hearings that lead to his firing.