He should be blamed for everything. If somehow, Avengers Infinity War isn't well received, Scott Buck is the man to blame. I think Buck's influence can be seen in the Defenders. The seeds of his incompetence are there. They were already probably Scott Bucking the Defenders somewhat. If Iron Fist had been successful, then probably all future Marvel shows would've used Buck's handiwork as a template. They already let him loose on the Inhumans before people actually saw how Iron Fist would perform.