I have read a lot of previous posts and the rating-system-based arguments for this unfair rule are simply not good.
The argument is basically like this: Someone leaves the site for good, times out of all their correspondence games which artifically depresses their rank and since they never play again, they inject these rank points into the system and never recover them which eventually inflates all ranks.
There are two reasons that this is not a good argument:
- This is no different from resigning and leaving or having a string of bad luck/being ill/being too busy to play well and leaving.
So, “timing out and leaving for good” is a very small proportion of the games that are mass-timed out and “timing out and leaving for good” is a small proportion of people leaving the site. Therefore, the rule does not really address the alleged problem and at the same time mostly concerns games that are not part of the alleged problem.
If the problem is indeed with people who are leaving for good, the solution should address people who are leaving for good (for example, by letting the influence of their last games on other people decay with time). I am not convinced that this does not happen anyway, but this would need a discussion how the rating system handles people who start at 25 kyu and then normally improve to 5 kyu without depressing everyone’s rank.
- With the unfair rule in place, it is more common for people to time out of games that they have lost (and again, that does not need to be by intent, it is easier to find a reasonable move in a won game than deciding what to do about the one that is going to be lost). So, people who leave the site by mass time-out will now take with them undeserved rating points which will eventually depress the ratings on the site IF it is actually true that without the unfair rule the ratings would be inflated.
The whole discussion has not at all convinced me that “the experts” have thought all these things through.
That said, fairness is a central property of a rating system. The onus to provide good arguments is certainly on the person who wants to sacrifice this aspect.