The quality of team play has always been bad, and it honestly hasn't ever been (at least for me) the people who leave early when they get downed.
If you want to talk about bad team play, talk about how people take forever to loot and get killed while looting. Talk about people ignoring pings, people looting dead teammate's boxes despite being close to a respawn beacon, talk about people who have microphones and don't use them except to tell everyone else on the team how bad they are, talk about teammates who don't split off to find their own loot and think 3 people looting 1 building is a recipe for success, talk about people who pop shots off on enemies 700 meters away with R-99s, talk about people who don't understand effective ranges, talk about people who don't ping better loot for you, talk about people who wait for you to open supply caches then take everything inside, talk about people who hoard grenades and don't pick up actual supplies, talk about people who pick up sniper rifles but don't understand positioning or who have awful aim, talk about people with microphones with bad callouts, bad decision making, bad aim, bad judgement, talk about the actions that your teammates take that drag down the enjoyment of the game for people who actually want to play with people who are just as good, or better than they are. Which, hint hint, is why so many people wanted a permanent solo mode.
Personally? All these posts that want people to be punished for leaving early are (in my mind) the people I get daily who can't get a kill to save their lives. All of them read the same to me, "I had someone who was gonna carry me to victory, but they left, and now I'm mad! They should be punished for not carrying me!" If I can't punish people for the things I've put in the previous paragraph, there's no real reason you should be able to punish me for leaving early, because I don't wanna waste my time watching brain-dead teammates flop around like fish outta water, missing every single shot with their current weapon. If your enjoyment of the game is ruined because someone left early, my enjoyment of the game is ruined because the people I play with haven't touched a mouse and keyboard in their entire lives. If it's infuriating to have someone leave as you grab your banner, it's DOUBLY infuriating to ALWAYS have teammates that are dead and NEED their banner picked up.