If you remove the leave button, your pretty much signing the ultimate death certificate of the game.

Exanple:

Johnny is a new player barely our of the academy, he joins a battle with no squad because he doesn't understand the game mechanics. But he's optimistic because he likes the theme of dust 514.

Johnny ends up on team A, moderately good players but nobody is anywhere near close to proto level except maybe 1 person, while the enemy team has 4 ancient exiles, 4 random guns, 4 Nyan san and 4 el eccinte Rio (I don't know if I spelt that right nut oh well).

Johnny's team is instantly red lined within the first 50 seconds. Nobody on his team is able to match their tactics, equipment level or communication efficiency. Every time someone spawns in they are instantly killed their only choices are to either stay in the MCC or instantly run further into the red line hoping they don't get shot in the process.

Normally in a game like cod, bf or any other game, you have the option to leave a game like that and look for another game that you actually have a chance at winning. So Johnny goes to the overhead screen hoping to find a different game but oh wait, the leave button has been removed from dust. Johnny wonders to himself why would a game like this force it's own players to hate itself. After seeing that within the first 2 minutes everyone on his team had died at least 10 times each and not a single person has a gotten a kill. Johnny waits out the battle hoping to find better ones aftewards. He encounters the same senario for 10 games in a row. Johnny instantly give up on dust altogether, biomass his character and Uninstalls dust.

Later that week at school a few of his friends ask about dust because they heard about it, he explains his experience and recommends they never try it. So they listen and don't bother even looking for it on the psn market.

This process happens about 50 times a day until there are absolutely no new characters being created thus, eliminating dust's growth and slowly every vet decides to leave the game because their tired of fighting against the same people over and over again. Thus dust 514 is finally dead. All because the leave battle button was removed.

This is what will also happen if you attempt to punish people for leaving battles.

No successful game forces it's noobs to be slaughtered constantly by veteran players.

Removing squads will eliminate the team nature of dust and pretty much cause more people to quit because they can't hang around with their friends or anything, unless you have something else in mind that would allow me to get into every random fight that one of my directors has.