See the thing is, I hate when someone says "yes i will do it", then you put tons of hours of planning into what you want to have done, suddenly they have a forum stroke and try to fade away into the sunset just to appear in the same section or different part ghosting like no one has not noticed you were online and be like "oh i didn't see you pm's" please >_>.
Alright, Devil's Advocate time.
What IF something serious comes up in said person's life? Or what if their job requires them to go away for a month (like I had to, though that was in the case of BoF)? We all have our lives to attend to and sometimes complications come up. Of course, I am aware you mentioned the missing person showing up somewhere else in the same section or elsewhere, but you never specified if it was an actual RP post or not. I get that it was assumed that it is an RP post, but if they were in the RP section and just posted something in the OOC, that could mean they don't have access to a computer and could've just made a small post with their phone. In the same way if they posted in a different section it could've just been a short post from their phone.
About the "Oh I didn't see your PMs" part, i'm not sure. Its definitely possible that the person in question did miss the PMs, I know I've done so before.
That is really all I had to say about all of that is that I just don't think it can be put so simply or generalized so much. That was a very broad statement, and I understand that putting a lot of effort into something just to have it die is kinda suckish. But what about the person who was part of the RP? If they put a lot of effort into their every post, they would want it to be as successful just as much as the creator of the RP. If they had to leave temporarily, they would also be disappointed that life has kept them from taking part in something they were enjoying.
I get that the story of RPs must go on and after a certain amount of unannounced inactivity, the show must go on, and I support getting rid of players that fail to post for an extreme amount of time without so much of a heads up that they would be gone for a bit.
Eh. I'm not sure how I feel about this RP anymore.