I’m not sure about the garage sale/flea market analogy, because even if Medium writing was something we’re willing to give away without financial compensation, we still get something for it: Self-expression, interaction, attention, practice.
I don’t know about the rest of you, but when I’ve got something rattling around in my head, I want to get it out. And once a few people started reading and occasionally commenting, including some people I’ve never met IRL, I liked it. I like it enough that when something gets more play than my average I’m happy, but less play I’m disappointed and second guess myself — even though interaction from the Medium community isn’t necessarily the best measure of quality (especially when you factor in the quirks of the algorithm).
I hold myself to a high standard for any article I write, but aim higher with Members Only posts. More in depth, and on something where I know what I’m talking about. Only seems fair.
The tipping analogy is pretty close, but not exactly right either. I haven’t fully wrapped my brain around the clapping/partnership program system yet — has Medium? is it even possible to understand it before seeing it run for a while? — but I’m getting the sense it’s something new.