Lichess needs to implement a fix to this problem.
It is clearly stated that such people who abandon their games will be punished for repeated behaviour, and yet people keep making new threads complaining about it.
I suggest some sort of bot which searches newly created threads for phrases such as "time wasters" "leaving game" "clock run out" etc. (Of course, the bot would contain an exception for this thread.)
The thread would then be sent to a "shadow forum" where only other people who had created a similar thread could see it.
I strongly believe this would solve the problem.