Some people who publish on Medium (me included) have a commercial arm which is trying to gain recognition from publishing.

Better known examples would be 37Signals and Buffer.

Increasing sales via the commercial arm is the aim and so being rewarded for publishing is not completely necessary. In fact I would consider paying for more premium features. Such as ability to restrict read next to particular publications or even pay for greater reach in other publishers "read next" areas which could then compensate them.

I also use Medium to publish personally with no real need for financial reward. I use Medium because it is easy and I don't get distracted playing with navigation or sidebar or thinking "I could stick Adsense on this and earn $2.00 a month".