Problems with coupled inductor SEPIC converter?

Hello,

Why does Dr Ray Ridley, one of the world’s leading SMPS Engineers, state that the SEPIC converter with coupled inductor should never be done?

The last paragraph, on the right hand side of the third page (actually called page18) of the following states that the SEPIC with coupled inductor should never be used.

https://www.electro-tech-online.com/custompdfs/2013/02/Sepic20Analysis.pdf


So what’s wrong with the SEPIC converter with coupled inductor?

I don't know why. He does complain about phase delay and error amp phas, etc.

He also said something about coupled inductors and that is not a real SEPTIC.
I build circuits with a tight coupled inductor that work well for me. Probably not a real SEPIC because I don't really pass power through a capacitor. From a distance it looks SEPIC.