It’s for voice, so that your mic is only active when you press an activation button. It’s how most PC games do it, and I would say it’s how most folks on PC use voice. It’s honestly a pretty basic feature, and super frustrating that it seems not to be a priority.
Don’t blame them. They are but a simple internet denizen born and raised in a world of walled gardens and proprietary protocols. The brilliance of the fediverse is blinding for they have never used their eyes.