This does give a good perspective on a way to work through a game project. Although breaking work into groups and classifying them to have a hierarchy to help planning, this feels overly simplistic and while some of the mechanics, aesthetics and dynamics can be controlled separately a good game will have them all intertwined.
Take Celeste for example. The themes of the game are overcoming challenges and perseverance in the face of failure. The art direction and level design show the player climbing a mountain, scaling to new heights, always working to get farther. The progression system gives many setbacks as in life but also many checkpoints, rewarding any forward work and promoting continuing and learning. The movement mechanics are difficult, forcing the player to try over and over again, learning from their mistakes. Each level introduces more mechanics and movement options to keep the player in a state of being challenged and learning constantly having to grow and push on.
Every part of the game works to the same aesthetic which could not be thought of last as the mechanics and system all work to the same end goal. To separate them into sections would likely create a sub-par game.