This has bad idea written all over it.
Oddly, I agree.
I'm going to be stubborn here, I think it's very important that a player getting a D rank for a long time should get an F. Getting a D 3 or 4 times is a strong signal the player is not going to change their ways. Remember, getting a D 4 times means that the player has gotten a D for a full year. I can understand getting a D once or maybe even twice, but three times? That's the kind of player that's not going to change.
I think we're seeing an F differently. I was seeing it as a ban from most games, yeah, but I was not seeing it as permanent. Most of the time, I figured it would be for a quarter or two, then the player would get moved over to a D. For starters, I don't really want to keep a list of F ranked players who stopped playing anyways (on that note, no F for ExKirby). Additionally, there has to be some kind of warning for players who've made grievous play errors but can shape up. I don't think a D rank is strong enough, but I feel a good warning would make the player change. I mean, if it's your first mafia game and you decide to ragequit, is a permanent ban really appropriate? On the other hand, I'm not exactly sure a D rank is a strong enough warning.
How about this? F-ranks can be permanent if all games have at least a C-rank requirement EXCEPT Beginner Mafia, which will obviously be N-rank (except the teachers, who must obviously be A or S), and Not-so-Beginner Mafia, which will have no rank requirements at all. I feel it's a good idea to give D-ranks a chance to redeem themself in one game, and NSBM seems like a good outlet for that.
I believe that would solve most of the problems and re-align me to how you were seeing the ranks, Dakarian. Looking at it from the host's PoV, it would look like this:
S-rank: Player who causes no problems, 100% guaranteed. Will warn about needing a replacement.
A-rank: Player you can reasonably expect to cause no problems, but you still might need to prod them. Will warn about needing a replacement.
B-rank: Player who may need to be prodded. Likely to warn you about needing a replacement.
C-rank: Player who may need more than one prod and is unlikely to warn you about needing a replacement.
D-rank: Player who caused problems in previous games. Unfit to play mafia, but potential to change.
F-rank: Player who caused major problems in previous games. Unfit to play mafia and unwilling to change.
As you might be able to tell, I don't see a need for an S-rank.
Oh, and Dakarian, I don't care what you say. Even if the player is alone, not playing to win can ruin the experience for others. Imagine if you were in the mafia and the survivor voted to lynch you and lost for it. I dunno about you, but I would be pissed. I just had a game win stolen from me! That's not fun, that's a player being an idiot. This is god-damn mafia, there are no good-guys or bad-guys. It's a game. Quit being an idiot and just play it. If you're not going to play to win, you're not really playing, now are you? So what's the point of signing up? Look, I can understand being frustrated at your mafia partners or inability to get cultists or whatever, but don't ruin the game for everyone else. If you don't wanna play, request a replacement. If you ragequit or act against your win-condition, you're changing the game for everyone else in an unexpected and negative way. Period. Negatively impacting the game should net you D. Can we agree on that?