In Massive Online Battle Arena (MOBA) chatting with the rest of the team is essential to discuss the strategies the team want to pursue as well as bond with other players, ask for improvements or congratulate them. But the chat channel needs to be easy to access, intuitive and easy to read. Otherwise it can hurt the game itself, because instead of playing the game and helping the team, the player would need to deal with the issues of the chat channel. Some gamers (mostly experienced ones) use mic/headphones to communicate to each other through a secondary software or play in the same room with different computers, but for all other users an intuitive chat is essential and can make all the difference in the game results.
Sometimes having a chat that can also deliver messages to the opposite team can improve the engagement of players through taunting, etc.
Example 01 (author's): League of Legends
Example 2:
Paragon
In Paragon, there is a chat option present in the game where the team members can communicate with each other and strategize about their moves/ warn fellow teammates of incoming danger. There are also shortcut keys that the player can use to quickly send across messages in the game to another player. The chat system helps the team to collaborate and as Paragon being a MOBA game requires lots of team communication, having a chat system is a boon.
Example 3:
Overwatch
This is another example of games which has really good communication system for their players to discuss strategy. It has both text based chat and voice chat. Text based chat had different channels which can be used to talk to the teammates and also everyone else including enemy players. You can even whisper to your friends or a single person, which is player specific chat channel.
IMG: As you can see in the image the blue channel is for the team chat (only the team can see it) and the brown channel is the common chat channel which everyone can see. Then there is pink chat channel for player to player private messages.