Question: If one chooses to use a form of character advancement wherein all player characters are granted an equal meta-rule improvement (such as experience points, attribute boosts, luck points, etc.) whenever they reach a benchmark (such as completing an adventure, accomplishing a mission, surviving a session, etc.), does it undermine the concept of rewarding player characters for clever play?
Answer: No. The meta-rule award satisfies the player for playing the character. The character's reward arises from the fictional setting itself as a result of the character's interaction with it. The player gets to see the benefits of levelling up, improving a skill, or gaining more ability to improve the odds, but the character gets to see the benefits of in-character choices based on whatever definition of success is important to the character, whether it's accruing wealth, building a reputation, gaining followers, attaining a position, solving a problem, promoting a social movement, exploring the unknown, telling new tales, or any other goal. The character's reward is what the character can perceive, not what only the player can perceive. Therefore, it is perfectly justifiable to allow player characters to improve at an equal rate with regard to meta-rule improvement, whilst basing their in-character advancement on their interactions with non-player characters and circumstances within the setting. Three characters who divide a treasure hoard three ways will be regarded very differently if one is a miser, one is a spendthrift, and one is a philanthropist. This is where experience points.