On YouTube I often find interesting content through the related videos side column. So I actually like the related video thing on YouTube. It rarely stops me from finishing the video I'm currently on. So something similar could be helpful on Medium too.

But maybe you're right and it is too distracting. I would have to encounter the related box a few times in the wild myself to know for sure.

As to whether the box increases or decreases your earnings probably depends on how many times you yourself appear in related boxes. I mean, if you appear in the related box of a viral article, it might drive lots and lots of traffic to you.