GRRM: "I was pretty much out of the loop After GOT Season 4"

"you get the famous creative differences thing – that leads to a lot of conflict."

I'm not willing to give D&D "dany kind of forgot lol, sansa is the smartest character lol, also we killed off barristan selmy because the actor got sad about it" any slack.

They should've given showrunning over to someone willing to carry things the rest of the way with passion and care. It's obvious they just didn't care anymore, they just wanted to film a bunch of cool battle scenes for a giant paycheck and then move onto something else.

HOTD's success paired with keeping GRRM involved only confirms to me that D&D were the main factor in GOT falling apart post S4. They thought they could do better than GRRM, they failed spectacularly, end of story.