Bandwidth doesn't grow on trees

I agree with that statement but I don't understand why it is necessary to disconnect me from calls when I'm the only attendant. Why can't you simply make it so when no one else is in the call, my Discord client just stops transmitting my voice (and video) to your servers. When someone else joins the call/voice channel the transmission could just resume as normal. Everyone would benefit from this:
Your servers wouldn't need to deal with audio/video that doesn't get transmitted anywhere else anyways, your users aren't getting annoyed because they are kicked out of a call just because their friend is AFK for a few minutes and less bandwidth overall is getting used for everyone involved.

Seriously I can't be the only one thinking of this and this can't be that hard to implement.