This is a feature so that smaller discords who don't want to make a lot of different voice channels for different reasons can have like a one for all voice channel for different needs.
So lets say you have voice channel that's capped at 3 people joining, and so person 1 joins this voice channel in order to play a game with their friends that's so that no others can interrupt.
So when this person joins the voice channel it becomes invisible to everyone in the discord apart from those who share the same game role.
This voice channel could be able to adjusted accordingly as well so that when a person joins the channel it can then also change room cap to adjust to the amount of players that can be in that game. If the person has more than 1 game role then they can select what game they are playing as they join.
This is a feature to mainly avoid making a lot of individual voice channels for certain games and having different caps on these rooms.