Game development process is already complicated as it is, but adjusting it for every possible player type - is almost impossible. Developers are looking for practical ways to make the game appealing to different groups of players, but the solutions are very rough and inconvenient. It is common to see following choice in a game:
How can a player know in advance, which choice will bring best experience?
Also consider the diversity of players. Some have great aiming (shooting) skills, but poor puzzle solving (or navigational skills), while others can be a complete opposite. All players want a challenge as too easy games are boring while too high difficulty is frustrating.
Imagine the convenience if it was possible to allow Artificial Intelligence to observe a player in real-time, learn particular skill-set and adjust the game to bring optimal experience without forcing the player to make explicit choices.