FF8 also had going to space and time travel. FF9 had a final boss that comes out of nowhere, yes, but immediately preceding that, the party leaves a parallel world introduced in the last third of the game to go to the origin of life in the universe, and that final boss is supposed to be a physical embodiment of death. All the way back in FF4, you defeat Golbez, then its revealed that he and Cecil are brothers and members of a race of people who live on the moon. And honestly, we can even go back to FF1, where you travel back in time by two thousand years and right before the final boss fight, Garland reveals he's been exploiting a time loop for functional immortality.
All I'm trying to say is, final act bullshittery is not new to FF, and 7R is nowhere close to being the most egregious one. It only feels that way because the game exists in a time where budget and technology make that suddenly ramped-up scale more obvious.