dont leave or feed - easy
This is not a deathmatch arena game, this is timing& lane dependent MOBA. If you don't have a stable connection, you are not eligible to be a participant in early access invite only game. Fix your internet and don't attempt to spoil matches for other 11 players.
what if people in this, early access game, experience bugs that make it barely playable. Again what if the power goes out? Or God forbid they have normal people things to do suddenly and had to step away for the game?
You're correct this isn't a deathmatch game so timing and lane management are incredibly important, if someone suddenly has to walk away from the game and deal with something and leave their character idol for 5-10 minutes they've basically missed either 1/6 or 1/3 of the match. their options are run around and try to catch up by jungling meaning the team is still functionally down a player, or they could try to help in team fights and plush objectives were they're probably just going to die and feed the enemy team. At that point what's the difference between them staying and leaving.
also there's no ranking system yet so no one's going down a rank because someone left, and there's no penalty for leaving after the first guy leaves, so worst case scenario gotta queue up again.
Also the problem is not people getting punished for leaving, leaving does mean that the game is basically over and everyone has to go find a new match, getting a penalty to discourage just leaving the second you start losing is fine, that's not what people are complaining about.
People are complaining about that either low priority queue is broken and you can't find a game, or our low priority queue is so long people give up and don't queue up if they get low priority queue.
Either way this temporary punishment for a lot of people has just become a permanent ban
it is the most terminally online, League of Legends player take, that if you leave again for any reason, you should get the same punishment as people that are being toxic and/or calling people slurs