I don't know if this is also directed towards me, but while I agree with what you're saying in general, you don't know what people have told Fuji beforehand. For my part, Fuji was aware of my availability before I even agreed to join the game. I went as far as I could go, but when it became clear that my availability was going to be sporadic, and it wasn't a game I could just afford to float by for 5 minutes every other day, I felt like I had to step aside. That said, there have been cases in the past where players have subbed out because of friction with players or for being suspected and so on. It's kind of hard to rule on things like that - for example a hard rule is pretty difficult to put into play because if someone for example is having a triggering episode, forcing them to stay in might be the worst thing for them and the community, so the cost of replacing them vs keeping them in might be worth it.
I also think with games of this size and format people just have to be realistic. Like as not, a fair few players sign up for the roles, to chat with friends a bit, and generally leave it at that. They're not signing up for the long deductive game that requires them to spend hours reading posts, thinking about them, and presenting their analysis in a compelling way. As frustrating as this can be for people, and believe me I could myself amongst the frustrated, the playerbase dictates the market as it were. If we had 20+ dedicated players who could provide good activity then it would be different. The only real solution is some smaller games, but naturally people don't want to host them, they want to include roles and characters they like.
At the end of the day we're talking about a thread that has had upwards of 7000 posts made in it. It feels a little off to be talking about inactivity there.