Why did structuralism fail as a working psychological learning approach?

Structuralism failed for numerous reasons. For starters, the data was incoherent and inconclusive because all research was mostly subjective and based on introspection. It wasn't possible to make a grand structuralist theory that would be examined using methods that existed and the system that was researched. Nothing was reached that was supposed to apply on a wide scale basis and it was eventually abandoned because there was no way to improve the methodology in any way