The defining trait of hero shooters is that everyone plays a unique role within the team. When people can't play the role they prefer (or when someone abrasively tells other teammates to switch to other characters), it often causes internal strife. This is the communications loop in far too many Overwatch matches, which is the most popular hero shooter.
Blizzard has a new method to mitigate these fights. It's implementing a role queue into Overwatch for both quickplay and competitive matchmaking. Before searching for a match, players select whether they'd like to play as damage, tank, or support characters. Then, the system picks two of each and puts them in a lobby together.
It's not a perfect solution. People might still argue over who plays as specific characters. Also, it doesn't guarantee a balanced team; it's seemingly possible to break from those pre-chosen roles and select any hero. But, Blizzard's mentality is that people will be happier if they're given the chance to play the type of role they prefer. Role queues should help accomplish that.
The changes won't go into effect right away. Role queues are available now on PC on the PTR. Then, they'll go into beta for two weeks beginning on August 13. Finally, they'll be implemented globally on September 1 when Competitive Season 18 starts.
Blizzard is making a similar change with regard to esports. Starting with Stage 4 of Overwatch League, which kicks off on July 25, teams will be restricted to a 2-2-2 format. That means two damage, two tanks, and two supports. The team composition meta (called GOATS) had skewed to three tanks and three healers, leading to way too many games playing out the exact same way. Balance is the goal for Overwatch right now, both casually and competitively.
Introducing Role Queue [Overwatch]
What's New in Stage 4 [Overwatch League]