I'm not sure if it's needed in Heroes; after all, the game is slow. But in dynamic team games, it's indispensable (Counter-Strike, Warcraft, etc.).
For best results, you should have a headset (headphones plus a built-in microphone) or separate headphones and a microphone. Using speakers is not recommended, as your teammates will hear themselves through them. This is because the sound arrives with a slight delay.
It can also be used instead of a phone for people living in different cities and those who don't like written communication (ICQ, etc.).
It doesn't use much traffic and barely loads the connection, which is very important for ping in games.
P.S. That's it in brief...