This isn’t about class imbalance, map prefrence, joining with friends, or any of that kind of “balance” or “quality of life” stuff. This is about a HORRIBLE game design issue that absolutely NEEDS to change.
This is about auto balancing. While this may seem like a nice feature, it isn’t, and I’ll explain why. At first glance, having the game auto balance the team for you when your team mates leave seems like a nice feature. The problem occurs when you are winning by such a large margin that the enemies start leaving, then the game starts taking players that should be winning, and puts them on a team that is often far beyond the point of return, often just a handfull of points before the game ends. It out right steals a victory from a winnig player, preventing them from gaining the bonus points, aswell as the satisfaction that comes from the success that they have earned.