Not really a priority. Just type the word "QUITTERS" in the search box to the right side and see what pops up !
At least, in days of flash, each member has a "light" next to their name, when they tried to join, or start, a game. The color of the light showed whether they quit sometimes (yellow light) or all the time (red light).
I do not know about punishments, but, with the light system, you would know in advance whether the other player(s) was a "quitter". I would like to see something like that integrated into new platform.