The problem we have here is multi-faceted. I can appreciate both sides of the coin, as I've been there before as I'm sure most you already have as well.
The problems are:
(a) Nobody likes playing up against the computer player, especially the Q, as it's a hollow victory, and
(b) Hardly anyone likes playing in what's obviously going to be a losing situation, where your territory slowly gets whittled away to nothing over the span of 50-odd turns. It's no fun.
The problems of imposing any form of penalty on any player is that if they know they'll be penalised, they can just whip out the old RL card and "legally" quit the game. Alternative methods of getting out of the game include colonising all ships and tax-killing all planets (ie suicide). A third method is to not put in three turns, and then put in a "ghost" turn so as to avoid being auto-dropped. Handing a losing situation over to another player is another devious option. Final option is to tough it out, and spend the next 30-50 turns regretting joining the game and/or your choice of race, as you're really not enjoying losing. I'm sure you can probably think of a few other methods of getting around the system.
The problems with a blacklist are (a) Administratively it's more work for our hosts, (b) Deliberately targeting quitters on the list in a new game is only going to make it harder for them in the game, and thus give them more reason to quit, and (c) nobody likes a bad reputation, and therefore they're likely to implement some of the aforementioned methods to stay off the list.
Therefore penalties of any form won't necessarily work, and we only have this current situation because peeps can quit without being penalised. Further, most players that quit do so because they see themselves in a losing situation and continued play isnt going to change anything (ignoring the genuine RL-issue players of course). Implementing some form of system to check to see if the player is *actually* playing the turn (rather than just processing the RST) is also unrealistic
From what I've seen so far, (IMHO) the best options are
(1) Start up the "no quitters" games. These could be renamed to something like "dedicated" games, "committed" games, or "to the death" games etc. This won't advocate the quitting of other games, but merely provide a game where commited players can meet.
(2) Have a threshold for normal games where it's actually considered okay to quit (say when score is 10% of the leaders?). Now before you get all up in arms about this - take the poor borg player in NF83 for example. His last starbase was destroyed ten turns ago, and he's only got two cubes left defending a couple of planets. With little fuel onboard and no means of building a new starbase, his situation is hopeless (heck even if he did manage to build a starbase, it would get taken by ground combat anyways). Nevertheless, he's still putting his turns in long after other players have already quit. Good on ya mate for sticking it out this far
but if I were in a similar situation I would have wanted to throw in the towel ages ago. I would not hold anything against him if he decided to call it a day on this one, as he's already gone well beyond what I would consider a reasonable threshold.