[nivaldoh]

A yelling crowd can be a dead giveaway that the other team is about to make a risky play under the fog of war, and give the defending team enough time to prepare.

For instance, if certain characters from one team are not showing on the map for the opponents and they suddenly hear a crowd yelling, they could anticipate that the character is about to do a surprise gank, attempt to solo Roshan, etc, and shut down the attempt more easily.

It can be heavily bias the decisions that players might make under certain circumstances, so it makes sense that Valve would go to great lengths to prevent that.