I have made the same mistake many others are making, i.e., trying to use normal, real-world logic to analyze Game of Thrones.
It is a swords and sorcery fantasy series. It features DRAGONS, a thousands of years old Night King who turns vanquished foes into zombies, magic curses, ravens which sort of talk as carrier pigeons, flaming swords, mammoths, giants, people who can enter the minds of animals ( and sometimes other humans), a prescient "Three-eyed Crow" who can reach across time to affect others, princesses descended from dragons who cannot burn. A 700 feet tall ice wall hundreds of miles long, maintained partly by magic, a world where the basic seasons are irregular. Summer or Winters can last for years. Etc. Etc. Etc.
An uncannily accurate big crossbow which can hit flying dragons is nothing compared to some of the basic plot points.
We have had to exercise a very large willing suspension of dis-belief to put up with the first 7 years. What is disappointing is how fast and how far the quality of the writing has fallen.
The writers have gotten cheap or lazy. Or BOTH.
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.
It is a shame. The series was always violent, bloddy and far from politically correct. There were shacking plot twists. Charactors were dishonest and often craven, but lately, they're just acting dumb.
It made unknows into household names. Nothing like this, spanning 8 years and almost a full world, has ever been done on TV before.
It's just a shame .somebody had to get greedy and ruin the final season.