How skill rating is calculated?

[tsokying]

How is the skill rating is calculated? Is it fair to add the same amount of points to everyone on the team?
For example, Merlin takes up more responsibility than Loyal Servant of Arthur in the game. The assassin made the final decision to kill Merlin, etc.

If we can add an MVP system? Let players decide themselves the MVP and add more skill ratings to the MVP.
Or calculate the skill rating based on the voting during a quest?