It’s just that a Total War game simply doesn’t change a whole lot between entries. This isn’t brought up to be snarky about Total War, the folks who review the games, or (certainly) myself. Even reviewers have to acknowledge that each new entry is much the same as the last in structure and art style, just as they did with the one before that and the one before that. Indeed, looking over reviews of past Total War games meant reading intros that are markedly similar to what I just wrote. Its creators, Creative Assembly, have a vision of what they want and they deviate from it rarely, if ever.
By this point, the Total War series is so woven into the fabric of PC gaming that it hardly needs explanation of its take on grand strategy.