All of these ideas seem to stem from the same source of a subjective and intolerant point-of-view, in my opinion. Ultimately, I agree with the sentiment of policing your own threads as you see fit but do not outwardly agree that any sort of reputation, karma, or blacklist system is productive as it only creates internal issues within the community. It is not being selective to impose these systems or ideas, but rather elitist and intolerant. Such intolerance of what is acceptable is greenlighting ostracization, exclusionary tactics, and other things that would shrink a community over allow it to blossom. 

I can understand inconsistency of activity is a large problem as I have had my share of activity issues or creative droughts, but we should try to understand people for their faults and try to allow them to better themselves and keep trying to collaborate. [@Lady Amalthea]’s system while understandable also does create that exclusivity and that atmosphere of intolerance that I mentioned to be problematic. As a GM I would look at former inconsistent players with an open mind and simply make plans for it if their character does vanish as their interest or time does.

A more crucial problem to solve is making the community realize overextension is more of an issue that needs to be challenged because overextension is the problem a lot of users moreso than it is flippancy. In fact I would say there are three types of causes that lead to the effects of “flaking”. These would include:
[list][*]Overextension
[*]Responsibilities
[*]Diversions
[*]Creative Issues[/list]
Now, if you ask me I would say that two of these circumstances are fixable and the other two are not. Thus it is my frame of mind that we shouldn’t have problematic systems like karma or ban lists, or even banning people from all projects because they slipped up on a few days. Responsibilities and Creative Issues are hard to work over, and you should try to help players rather than give them a scarlet letter.

Help people not overextend and help them focus. Help, not judge.