Ya i could never use insect frass as a medium, and i would never suggest to. And as far as a standalone nute, i dont think it is intended for that either. It has an npk of 2-2-2, but i would never use it as a base.
I know that frass not only contains insect castings (which if ur familiar with the soil food web, sometimes it takes an insect to ingest an element,than rid it either in their castings or whether the elements are withheld in its bodies, from there its either root available or eaten up by microbial life and passed on down)but the frass has crushed up insect exoskeletons. The body matter immitates a predator bug when it nears the root system. Ur plant thinks it is being invaded and kicks into over drive sending the metabolism to a high level. Since there is no actual problem to fix, your plant benefits from the boost completely.
The body matter also irritates other predators such as fungus gnats and root aphids. Its almost like a fiber glass to them, also their larva cannot pupate in such harsh environment.
There is other benefits, im not aware of them all. I use it in 3 ways and will never look back: mend in my. soil, mix in my brew, and foliar. Each method has its own trick.Z
