Another day, another thought. The closest situation to groups.io that I can think of is Meetup. A couple of years ago Meetup, which was formerly free, started to charge group owners a yearly fee. It provided group owners with a means of charging their members, but members were free to pay or not pay. I never owned a group on Meetup but I was formerly a member of a couple of them. And I remember that the member payment was optional per group. There is no way I would have stayed in Meetup if I, as a member, had had to pay a yearly fee simply to belong to the platform. And I think what it comes down is that's because I, as a mere group member rather than owner, did not have an investment in the groups I belonged to. I could participate as much or as little as I wanted to, I could disappear for long periods of time and come back (and having had to pay for all that time in between would have been a dealbreaker). So in thinking about the general philosophy, equities, and psychology of whether to charge just owners (who then could, if they so desired, request optional reimbursements from members) or charge members directly, I think it comes down to just that: who has the real investment in a group. And that's the owner.
To the person who scolded me a few days ago for posting what I didn't like about Samuel's plan without suggesting remedies ("criticizing without providing solutions," I think he called it), I refer to Mark's original post in this thread. He specifically asked for problems and why it should not be implemented. He did not ask for solutions.
And now I'll go hide under a rock again for the next few days, until something else occurs to me. :-)
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