What's shady about asking people to pay for content? It seems like it's pretty much out in the open so you can take it or leave it, not secret or covert or shady in any way.
Nothing is wrong with paying writers. But I do have a problem with the Medium bait-and-switch. They offered a great interface for writing and publishing content that is free, and then years later start charging for access to that content after millions of people have published articles.
Did you think that it would remain completely free (and ad-free, which was its major selling point) forever? I actually quite like what they're trying to do with their new business model.
