So you're asking to prove a negative with respect to blacklisting?

Some factories have been caught physically locking employees in the building and not letting them leave. Can I say with certainty that this isn't happening at Id? No, but it's still not valid to baselessly assert that it is happening at Id Technologies because other instances of this behavior have been documented.

The fact that desirable jobs like game dev means employers don't have to compete as hard to attract talent. That's not infringing on game developers' rights. Game developers have the ability to work in jobs other than game dev. If they choose not to pursue those opportunities that's a choice they're making on their own initiative, not an infringement on their rights.

Workers rights like safe working environments, minimum wage, and other laws still apply to game devs.