messages to winners and losers

Sometimes I want to tell my appreciation of a good game to my opponent, and I feel, yet have no proof, it will benefit to him/her playing more. So, in a nice world, with this feature I would get my kick and lichess would win too. I want to talk to my opponent after the game had ended. It doesn't really matter what form the conversation takes, direct messaging or notifications towards unread chat of a game. What matters is my care of the game, and the pride that the winning opponent reads of it. Can you add like some notifications of messages opponent writes on a finished game? Or are the such messages correlated to less games played, surprisingly?

why can't you just type it in chat?

I guess because the opponent usually leaves immediately after the game.
I can understand @edgedg but I don't know a solution. Maybe write them a private message?

@edgedg Yes its like a one night stand when the other leaves without cuddling afterwards :(