And not one of these ECFs writings were ever declared Scripture by the NT Church. Not one.
Further, when they are opposed to one of Rome's other doctrines, do you still cite the ECF or just say they were in error because it doesn't line up with Rome's beliefs?
By not adhering to Scripture as the sole source of doctrine you're having to jump between which ECF you want to believe on the various doctrines of Rome.
Additionally the door is left open for any new false doctrine to be introduced such as the Fifth Marian Dogma currently under consideration.
sola scriptura is such a bonehead idea, it is a trap to keep you away from the rest of your patrimony.