Hi Kristina, I work at Medium and just wanted to chime in to clear up potential confusion or misinformation here - we announced our Mastodon instance in January, but we only just opened it up to Medium members recently. We emailed folks who were on the waitlist this week to invite them to create an account. We'll do a more official 3MR announcement about it next week, and then we'll do more to communicate it widely. I'm a big fan of Sarah Drinkwater's writing on community-building and on creating "products with community at their core" - and she writes about how community and scale are often at odds.
Another reason for this tiered approach is that we wanted to scale in stages to make sure things work on the technical side as we ramp up - to work on it behind-the-scenes, build integrations into the Medium membership, test the limits of our servers, etc. Since Mastodon is a decentralized platform, it's on us if all the servers crash ;)
All to say that I think proclaiming it "dead" may be a little like saying a party is over before it starts, in this case. Personally, I think the local me.dm feed is just starting to get fun this week as writers begin to join and share stories and test it out. I hope you give it another chance!