I wouldn't say that. Thing is that policing the activity or lack of activity in this case should be left up to Rpers and Gm's and shouldn't need to be the job of moderators.
My system works for me, I wouldn't expect it to work for others.
I don't auto deny people in an RP unless there is a major issue. (Flaking I don't consider a major issue.) In fact I only have 1 person on the forum currently that I would never allow in an RP of mine again and that isn't because of flaking. Do I have a list of people that have flaked out in the past or been kicked? Sure do. Doesn't mean they won't get another chance, just means things will be worked on if they join another. If I see they are already stretching themselves thin, I will ask them about it. I have had plenty drop Rp's without word and join one of mine.
I have had plenty of people step down from Rp's and come back later if they couldn't post for whatever reason (creativity, stretched too thin, illness, etc). For me I just expect those that join my Rp's personally to keep me in the loop. If they drop, just let me know. I don't hold that against people. I've had to drop Rp's I have been in for various reasons - thing is I don't just vanish, I let the GM know in the OOC.
I wouldn't expect any Gm to hold their Rpers in their Rp's to my rules, or visa-versa . That would be ludicrous. It's like hearing my kids go "Well Tommy's mom lets him!" if I tell them no on something - Yeah, well I am not Tommy's mom. Same goes for RP. People know what they are getting into when they join an Rp of mine, I hardly leave anything to guess in terms in rules and expectations. If they agree to it, then they can join. Then I make sure they are be held to it. Not only for my sanity but for the sake of my Rps and the other Rpers.
Again, I think it boils down to the Rpers and the GM's and for them to handle it as they see fit. Each GM is different, each will lay out the rules they want, they will enforce them as they see fit. Personally I see it as their right as a GM, they are taking the time and effort to put forth the RP. Once I step into another persons RP I am not in charge - That GM is God in that world. I don't like it, I can leave. I stay, I as an RPer am under an obligation to follow their rules. (Doesn't matter if that is post every day or sit there wearing a tea cozy on my head while I post and include a picture of it.) Their house, their rules.
Sure, we can work with people and most of us GM's do. We give reminders when people need to post, give them extensions if something comes up, we are there if they need to step out for a bit, we shelve their characters for a time if need be or bunny them off scene, we work them back in when they come back. Over time we learn their work schedules, when they have exams, when they get sick, who they just broke up with, even when their is a death in the family. Most Gm's are secondary advisors to their Rpers behind the scenes. We do what we can so an Rper is better for being in our RP.
But this all really boils down to Etiquette, that is something that I personally feels need to be taught more in Rp's but again, I don't believe that is a mod job. Hence why I am against a system that marks people for flaking out. If a Gm wants to set a standard that states you can't have flaked out before for any reason - that is up to them. Do I think it is a good idea? No, but then again, not my RP. For me, my rules are out there, they agree to them I'll work with them as long as they follow the rules they agreed to when they stepped into my RP.
As you said we need to work with Rpers and yes we do - each Gm should work with their Rpers - Their Rpers are what keeps the story going. Gm's need to let their Rpers know that if something comes up that their Rpers can tell them about it. Most Gm's won't hold it against someone if they leave as long as they are told. Takes all of five seconds to post in OOC or pm the Gm and say - Hey, I need to step down for a bit. Granted there is a vast difference between going ghost and pulling out of an RP.