Also, the OP post sort of encapsulates why people (including David Benioff and D. B. Weiss) seem to misunderstand the Red Wedding scene and its legacy. The scene isn't about "shock value." It's not like George R. R. Martin decided to throw darts at a dartboard and went "Welp, I guess Robb Stark is gonna die in this chapter." It's not some random heinous event he threw into the book to shock people. It's the logical culmination of a series of severe tactical mistakes that Robb makes throughout the books. In a traditional fantasy story, Robb would suffer no consequences for these mistakes because he's "the good guy" and a noble man, but ASOIAF is a realistic world where people who make mistakes pay the price for them.
The correct reaction to the Red Wedding isn't supposed to be "Holy shit, I didn't see that coming," it's "Holy shit, why didn't I see that coming?" That's what makes it a good twist and that's what its many imitators fail to understand.