It’s a tool! No one claimed it was a silver bullet!
Threat modeling is yet another input into an over all risk analysis. And you know what? Risk analysis/Risk management, whatever you want to call it won’t be perfect either. Threat modeling is in itself a model. All models are broken. We’ll get better at it.
But claiming that something is a failure because it’s not perfect and that it doesn’t always work, is one of the cardinal sins of infosec from my perspective. Every time we do that, we do ourselves and our industry a disservice. Stop letting the perfect be the enemy of the useful.