I’m sure most developers think they need to stick to the concept of “end game with a huge climax” like a movie, hence a big epic battle against a big enemy.
But, one game I can think of that bucked the trend is The Last Of Us. No final boss, just a final level, an escape sequence, and done. And I don’t think anyone complained about the absence of a boss because the game was so well done and what they did worked just fine as a climax.