Inclusion is an important thing in video games. After all, a game with a high difficulty curve at the start doesn't make for good first impressions, but it has to stay exciting after a large amount of hours have been put in. What do you do? If you make the video game based solely on chance, it would get unpredictable and frustrating quickly. After all, who wants to stick around for a game that could be won or lost without any recognition of your own personal skills?
But if you make a game based on the player's skill only, introduction of rigid set of rules and situations is introduced and it becomes too easy for veteran players to dominate the field. In a team based co-op video game with multiple players on each side, this is not a good thing; the introduction of trickling mechanics such as random critical hits (for example) would enable a more even playing field for low level players against high level players, ensuring that while they can achieve victory in battle and not feel overwhelmed at being far less skilled than their teammates and enemies, the random nature of such does not guarantee that the lower level player will always win and they have a chance to adjust to a situation accordingly and learn to play the game.
But if you make a game based on the player's skill only, introduction of rigid set of rules and situations is introduced and it becomes too easy for veteran players to dominate the field. In a team based co-op video game with multiple players on each side, this is not a good thing; the introduction of trickling mechanics such as random critical hits (for example) would enable a more even playing field for low level players against high level players, ensuring that while they can achieve victory in battle and not feel overwhelmed at being far less skilled than their teammates and enemies, the random nature of such does not guarantee that the lower level player will always win and they have a chance to adjust to a situation accordingly and learn to play the game.