I think we're seeing a similar problem just from different sides. Why make the experience more seamless if the content at the end isn't also worthwhile? You're working left to right, I'm working right to left.
If it’s not seamless then people won’t see the value to generate content in it. So you will get more garbage content.
If much of the content is garbage but some is good then presumably people will still come for the good stuff and just spend more time filtering out garbage. Most people don’t navigate inside the medium ecosystem anyway. So inner system garbage is less of a problem then landing experience
The issue is how annoying it is to experience the content, not the content itself.
And wow, quite a claim to say that creators are too busy to have lives worth writing about.
Reconsider what went wrong with Medium so you can get on the right track.