The final season of Game of Thrones is over, and with time and space to look back on the last two seasons, critical and fan consensus is settling around the idea that the final season, or two seasons, were "rushed." The imagined justifications vary; some say it was because showrunners David Benioff and Dan Weiss were tired, others say they were burnt out, and still others allege they were just ready to move on to get to Star Wars. Regardless, the argument is the same: More episodes in Seasons 7 and 8 would have fixed the problem, or more seasons in general would have helped with the ending.
But this feels like a misreading of the last two seasons, which weren't rushed so much as they were thin, and lacking material. In short, the final two seasons, despite everyone's best efforts, couldn't cover for the lack of A Song of Ice and Fire novels from author George R.R. Martin to adapt.
Most fans of adaptations know the old adage of movies vs. books, in which the film adaptation is just the tip of the iceberg, with the books having miles of depth below the water. (In the Harry Potter fandom, the meme using the “Below The Surface” poster of Saint Basil's Cathedral to illustrate this principle was very popular in the mid-aughts.) After all, taking a 600-800-page novel and condensing it into a two-hour film, or, in the case of Game of Thrones, a 10-hour season, inevitably necessitates leaving out various characters and subplots to make sure the main story fits.
But even when an adaptation leaves out hundreds of pages of discussions deemed "unnecessary" or "distracting," or cuts fan-favorite characters due to casting limitations, the worldbuilding those plots and characters help define remains. For instance, Game of Thrones may not have bothered with Lady Stoneheart, but her travels around the Riverlands help set the chaotic tone for the war-torn lands in the wake of the Stark collapse, which the show drew upon as others traveled up and down the Kingsroad (or off the beaten trail of it). Quentyn Martell may be unknown to those who only watch the show, but the secret Dornish alliance with the Targaryens his trip to Meereen revealed helped guide choices in Seasons 5 and 6.
Moreover, when the show needed a scene to help pad out a plot or build characters' motivations, the showrunners could pull from some of these discarded materials. Game of Thrones' original pilot, for example, famously failed to establish that Cersei and Jaime were twins, because the opening novel, A Game of Thrones, has no chapters from either Lannister's POV, and therefore does not include a scene where the two just sit and privately talk. To fix this, Benioff and Weiss borrowed a passage out of the fourth novel, A Feast for Crows, where Cersei recalls looking down at Jon Arryn's body and used that to create the establishing conversation.
Almost nothing else from that section of the novel ultimately made it into the show. But having these Cersei POV scenes for the writers to draw upon when necessary turned out to be crucial.
And then the show passed the books.
Despite everyone's hope that The Winds of Winter would come before the show ran out of material for good, it didn't happen. From about mid-Season 6 onward, the series simply no longer had that cutting-room-floor material to dig through and reappropriate to help fill in the subtle moments of character development. Thankfully, there was enough action to push through to finish Season 6's 10-episode run. But once that was over, the showrunners only had a bare-bones outline for the final seasons.
One could argue it was the show's job to make stuff up, to fill in where those scenes were not, to imagine and create those moments that would give Jon Snow and Daenerys Targaryen's love story space to blossom, and time for fans to not only buy into it but fall in love as well. One could insist the buildup to the Battle of Winterfell deserved more time too, and that it should have been the ninth installment of a ten-episode Season 8, and that Daenerys' dictator turn deserved a full 10 hours to develop as well. But for that to have been the case, Benioff and Weiss would have, in essence, had to write George R.R. Martin's books for him. To ask one set of writers to step in and invent the story that another has not yet finished is unfair to all parties.
The show did manage to create some characterization in small doses. For instance, writer Bryan Cogman's "A Knight of the Seven Kingdoms," the second episode of the final season, made an entire 50-minute meal of the three-word plot point "Jaime knights Brienne." But that's not a sustainable proposition, and certainly not one to demand to go on for seasons at a time.
Asking Benioff and Weiss to write the last two books for Martin was never going to happen. They did the best they could, but without the magic of the novels, and the substructure they provided for the show to draw upon for all those years, the final season was never truly going to satisfy fans. It would always feel like a shadow of itself. In the end, the show as viewers knew it simply couldn't exist properly without the books.