My advice to you is:
Play ranked. Very few leaves early in this game mode, at least when you get to like high silver/low gold or higher. The only real difference between ranked mode compared to pubs is precisely the leaver timer so it seems like a winwin. But if you for some reason dont want to, then your only option is to play with premades in pubs. Because bottom line is that a leaver timer in pubs would make this game unplayable. I would accept a 15 second timer before you can quit just to prevent those who quit even before they get knocked but imagine the rage and frustration if you have to wait 3 minutes after your random teammate ran away in the middle of the fight
