I cannot in all honesty say they have not. I have not seen enough of Medium rewarding readers who simultaneously are writers on the platform for engagement with either of other writers or readers of their content.
In an imperfect world, however, the way I see it an imperfect Medium is better than no Medium at all. What I mean is a social media world consisting entirely of Facebook, LinkedIn, Twitter and Instagram is a worse outcome than one which in addition consists of an imperfect Medium.
Thanks for taking the time to engage.