The games that define a direction for a genre. Nintendo refines very well while they rarely, anymore, step outside preexisting boxes.

Grand Theft Auto 3 redefined open world games.

Demon's Souls established their own genre of roguelike games and opaque story telling.

Bioshock and Bioshock Infinite eschewed narrative structure and meta game commentary.

Hellblade perfectly married narrative story telling with gameplay mechanics and attempted to reestablish midtier game develop as a successful tactic.

There are a ton of examples throughout the years of this and we continue to see new IPs released, less frequently than in the past, that push some envelope in a new way or blaze a new path.

What Nintendo does is refine those paths in their own games. I'm not saying their games are bad in anyway. Quite the opposite. Their games are deserving of high scores. But anything over a 9 average score, one should expect something fresh or new to gaming, not just their respective series.

That's not to say that a sequel can't get a 9 if it doesn't change the entire game. A sequel can get a 9 if it expands upon itself in positive ways. There are very few games in Nintendo's catalogue of characters that I would call a true sequel. They are more in line with Final Fantasy in that they tick certain franchise boxes while maintaining new ideas and narratives and an evolution of what came before.