I think many RBLs started out with good intentions. But it does feel like like many of them have shifted to pure grift. Pay for "priority" review definitely has negatively impacted this. UCEPROTECTL3 especially feels like an extortion attempt similar to the threatening domain renewal scams. But I've never notice any outgoing email from my services being blocked by it. So it just goes in the crank file.
Really we probably need some sort of anti-RBL system. To keep good actors honest and force bad actors out of business.