I mean, the fundamental premise of formal methods is that assurance of correctness is achieved through unambiguous specification/modeling and mathematical proof. The extent to which you're dependent on dynamic testing of actual code to achieve assurance does speak to the extent to which you're really relying on formal methods.

That’s literally what the post is about. I don’t see your point. The post is saying that formal tools currently do not handle performance and reliability problems. No one said otherwise.