I see this point often - and similar ones about entitlement - but my reaction at the time to both Mark and _why was one of concern: they were people whose work I absolutely appreciated, and who I therefore appreciated as people. When they vanished abruptly I was concerned for them on a personal level, and naturally I wanted to find out if they were OK.
The unfortunate consequence is that concerned checking in doesn't scale well, and is indistinguishable from mob action to the person being checked in on. (Which is how it played out, if I remember right). So even though the person certainly doesn't owe anyone an explanation, it can be in their own best interests to provide enough of one to curtail concern.
I understand and I agree with you for the most part. Most of what we're discussing exists in a grey area to me, one that can only be clarified if we differed to real-world norms at the expense of forfeiting some of our natural inclinations in a digital space. As much as it may be in a person's best interest to provide an explanation for their exit and expunge from an online community, I'd offer a similar argument, that it would be in the best interest for certain people to differ the responsibility of checking in on the person's well-being to those who are known to have an actual relationship with them (i.e. one that isn't predicated by the environment that the person is tearing themselves away from in drama-inducing fashion). I think that this where scale becomes an issue, like you said.
The unfortunate consequence is that concerned checking in doesn't scale well, and is indistinguishable from mob action to the person being checked in on. (Which is how it played out, if I remember right). So even though the person certainly doesn't owe anyone an explanation, it can be in their own best interests to provide enough of one to curtail concern.