Here's a scenario you might want to think about with a "merit-based" system.
The dispatcher gives you X fuel.
In your experience and interpretation of the weather situation, you want X+Y fuel.
If you land make your destination and didn't need Y, then you wasted company resources despite what your dispatcher thought.
If you end up diverting or holding and land with Y+minimum IFR reserves, you're a hero.
Same decision, same weather, but two entirely different outcomes for judging your decision.
The dispatcher gives you X fuel.
In your experience and interpretation of the weather situation, you want X+Y fuel.
If you land make your destination and didn't need Y, then you wasted company resources despite what your dispatcher thought.
If you end up diverting or holding and land with Y+minimum IFR reserves, you're a hero.
Same decision, same weather, but two entirely different outcomes for judging your decision.