Supporting quitting-without-resign behaviour is unacceptable, and that's what both people minimizing the problem *and* Lichess are doing. One must understand a few quite obvious principles:
1) When you are playing chess, if you quit, you loose. That's a rule. If you didn't put down your king before leaving, the referee MUST do it in your behalf.
2) A player's connection problem must not become his opponent's. Lichess should take care of that by automatically assigning victory to the player still on board when his opponents goes offline for more than 30 seconds, that's more than enough. Otherwise they are forcing caring players to waste their own time because of less caring people's problems.
3) Warnings in the chat window is completely useless because nobody comes back to read the chat AFTER leaving a game.
4) Any punishment 'after', that's a very childish and ineffective way to address the problem, because 1) new players keep on coming and they always do the same thing, 2) you could hit people whose connection just dropped, and the only effect you obtain is pissing them off and have them start sympathizing with 'real' leavers, or simply move from Lichess to
Chess.com, where they simply auto-resign ANY game after 30 seconds, so no punishment and no hassle for anyone.
5) In Lichess, leavers can even start a new game when their time is still running in the game they just abandoned without resigning. This is outragious! It can and must be stopped immediately. No excuse for Lichess allowing it.