This is because a significant amount of the cognitive labor involved in producing truth is codified in the scientific method, which every practitioner can be trained to follow. Philosophy has developed no such innovation.

Um... you do realize that PHILOSOPHERS developed the scientific method, right? That was not something scientists just came up with on their own. So, when you say that philosophy has developed no such innovation, you miss two things.

First, philosophy did come up with that exact innovation, for science.

Second, scientists have not come up with any such innovation, for themselves or others.