In the books Euron had a horn that could control or at least disrupt dragons. The insanely accurate Scorpions (railguns) I think are just a plot device just dumbing down the story instead of wasting time adding another supernatural layer.
The Battle of Winterfell was a spectacular fail, designed to appeal to the lowest common denominator. If Emilia Clark's Episode 5 comments are correct, Sunday night sounds like another spectacle.
I worry we're already seeing the hand of Netflix dumbing down the HBO quality, seeking monster ratings but mediocre writing/film-making.
HBO is going to be furious. They're planning spin-offs/prequels, etc. They can't be happy that a large portion of their fanbase is furious and absolutely ready for this thing to end. Hell, I was happy today when I learned there were only 2 more episodes instead of 3 because I can't take anymore and I've ready every book, novella, hardcover, etc. available. If you're losing people like me, you're in trouble.