I don't understand why this is a thing. It's just annoying.
When I first make a server, there has not EVER been a point where I join voice chat immediately, and this is for several reasons, the main being that I'm the only one in there because I made it seconds ago.
There have been many instances where I'm talking to someone, and they'll be mid-sentence talking about a server they're going to make and they get disconnected.
If I want to immediately use voice chat in a server I just made, I'll click on the voice chat. It takes less than a second to do. It shouldn't happen automatically.