Penalty for leaving players

Hell no! Here's a scenario; you just got killed by a player that has over 5000 kills, your team mates have less than 20 kills, still have white armour, a P2020 and a Mozambique. You already know what the outcome is going to be, why waste my time forcing me to watch them die?

And the amount of toxic players in this game... Why should I be forced to stay in game with them?

If they add a solo mode, then yeah add penalty for team mode, but for the time being, no.

Good players can still win a game solo. This isn't overwatch where you need a team to win.