It’s an interesting debate started by @farrtom; UGC has it’s issues as pointed out by @simplygrey but remember that Direct Messages are different than public group chat… a pissing match there is less impactful to the community than in a public forum or thread.
That said, … the mere fact that @medium even let’s people leave comments (both threaded and in response at the end) at all has opened the door, they should give you better tools to engage with that interaction or not allow it at all.
My other issue with @medium is that they do a terrible job in just showing users and alerting them to the responses on their posts. Even today, I noticed a “2” red counter bubble on the @medium mobile icon, when I opened the app, nothing directed me to any type of interaction. I had no idea what those two indicators were even referencing.
They need an inbox first and foremost to show me where all of the interactions with my content are. Then second to allow me to respond and interact with those people if I want.