Edit: I'm aware that the article is mainly about the lack of compensation for the artists behind these pictures. But if it would not be worth their time, I'm sure they wouldn't go down that road continuously. Having their pictures attributed all over the net can increase their reach. I'm sure they upload these photos mostly as a second hobby, after they sold their best shots, etc.
If Unsplash ever gets monetized, just use pixabay. I've been using them all the time, because most Unsplash pictures you see have already been used in someone else's story somewhere.
Also, the search function on Pixabay turns up many more relevant search results for a topic or keyword, compared to the limited In-Medium search bar, which seems to completely ignore a second keyword or take it completely out of context.
It's not as easy as clicking on the plus, typing a keyword and clicking on the first picture you like, but to make up for it, Pixabay offers far more and more varied pictures overall.
If you've not tried them out yet, make sure you give them a visit.