Welcome and good luck! A few thoughts:
1. The algorithm needs work. I don’t enjoy most of the stories shown to me, and that is not good news. Medium needs to refocus on the reader experience.
2. Readers want curation to a certain extent. We don’t only want to read Tim Denning, but the number of stories I come across that need significant work is surprising.
3. As an author, we need better stats. I have to spend hours each month keeping my own stats because otherwise I don’t know which stories are earning money, etc. it is not just about reads. Even just adding a “total earnings” to the main stats page would be a major help.
4. I like the idea previously mentioned about being able to recommend stories to your followers. That is one way to crowdsource curation. These stories could even be kept as a section on an author’s homepage so that their followers can go see a list of recommended articles.
5. Need to have private messaging with other authors and even readers. It is not easy to build connections when everything you say is in public. Currently we have to go off Medium to have those conversations. Why would you want us to do that?
6. Should look at continuing to build functionality and integrations for content creators. Why not be a “one stop shop” for great content creators? Email responders, connections to Gumroad or similar, etc. Creators now have to send people off of Medium to do these things. You should want people to want to stay on Medium more. They will read more, write more, and recommend the system more.
7. I’ll mention it again, focus on the reader experience. How many more people would sign up if they saw higher quality work when they looked at Medium? Curation, recommendations, the algorithm, etc all need to be improved.
8. Medium would probably benefit from bringing in some more big names and getting them set up. Very few people who are big names outside of Medium choose to write here. Many people are writing about things they don’t know or understand well. Story content is poor.

Best of luck!