You like to blame the Principle Shader for the decline in Shader quality (of the average user), but I’d like to turn that argument around - its not the principle shader, its the fact that the BF did not put more work into its development, like all the other competitiors did.
Cycles principle shader is not really great for the prupose of doing photorealistic images and it gives the user a false sense of security. The other über-shaders the competition provides are fit for purpose, they don’t suffer the same problems as they have versions/variations of principle shaders that went through several updates.
In Pixar’s Renderman, the principle “Disney shader” is considered (ancient) legacy.
It was a (good) starting point, but only cycles is still at the start while the others started to sprint away 3-5 years ago.
Btw: Renderman also shows how to solve that problem with the conflicting user demand for realistic and stylized:
