I sometimes like to join 6v6 or 5v5 maps, and when I do, I usually have to rejoin (or someone else does) at least just once because of connection problems. However in the short timespan I'm gone, there is a good chance that another player will join and think the spot is empty. They will then (through no fault of their own) take that spot and it's a hassle to fight over that spot if people aren't cooperating. I've seen long drawn out fights in the chat, and it goes on for 10 minutes before the game even starts.
That is why I would like to request a "Rejoin" button. After clicking on the button and following the "Are you sure?" prompt, you will be ejected from the game and immediately rejoin. As you leave, your spot will be locked until you return.