> Agreed, if people cannot listen to the simplest commands, what makes you think they'll obey a leader?
When some random person starts shouting orders, people generally don't know if it's some idiot or not. If a person had any official leader status, most people would listen -- especially those who voted and agreed to follow. For those that don't listen to anyone, nothing can be done. Still, this would be much improved. At the very least, newbies and people who want to work as a team would have a central, agreed-upon authority to get direction from. After a leader shows his worth and wins games, more people will gladly follow.
> What makes you think they'll even vote a leader?
Why wouldn't they? Here is a simple implementation: Once per game, anyone can call a vote to install themselves as leader. Everyone on that team gets a yes/no prompt. If there is a majority of yes votes for any person, that person becomes the new leader. It's a simple question: do you want this person to be responsible for directing the team this game? People who choose not to vote get no say in it. I think that most people would like to have their say. If no one gets voted in, that team loses the advantage of having someone coordinating them.
> What if the leader sucks?
Easily remedied with a new vote. Once a leader shows incompetance, people will stop voting for that person. After many games, good leaders will stand out.
> So, what would team leaders actually be able to do?
Primarily, a leaders' speech would stand out. This is all that's necessary for a huge increase in coordination. A line of text saying, "Leader of the Humans says: everyone, stop feeding and stay in base," has much more weight than a random player saying it. Having the leader stand out physically is also a good idea -- killing a leader, or at least keeping him busy by fighting could disrupt coordination of the enemy team. I imagine that those two things would be easy to code. Other possibilities come to mind that might not be so trivial: denybuild powers, kick from team powers, etc. This could be an option for servers that want to force obeying leaders, but I don't think it would be necessary. Most people are followers by nature.