Excellent question!

I too am finding the loss of talent on Medium quite disheartening. Things I’ve noticed that are possible/probable contributors to the current state of Medium can be easily summed up with some examples (aka the 7 Sins of Story on Medium):

1. I was presented with an advertisement for a Locksmith as the first story I the Latest Fiction tag yesterday. Seriously!?! Please Report advertisements like these to Medium as violations. Clearly they do not meet the criteria for fiction or story for that matter.
2. The fact that nobody (Medium or members) seem to care that anyone can post anything anywhere (see point 1. above). Whatever content a person uploads is placed on Medium according to the category or tag that the person doing the uploading chooses. As a result, Medium is becoming an un-curated source of spontaneous drivel including blatant advertising that is now permeating a once vibrant community of writers and readers of Fiction and Short Stories.
3. As you mentioned Lisa, Medium seems to be more of a social platform now than a go-to community for the latest examples of creative and inspirational writing. And the individuals presenting the social chatter clearly can’t tell the difference between reality and fiction as they continually post their ongoing flame wars and discussions under the tags Fiction or Short Story. Perhaps Medium should provide a dictionary for the consistent offenders who aren’t aware of what the words Fiction and Short Story actually mean.
4. Another thing I’ve noticed is the perpetual uploading of story after story after story in a row, perhaps in a misguided effort to gain readership?? I don’t honestly know. Maybe the up-loaders mistakenly equate app real estate with good writing? NEWS FLASH: I’ve made numerous attempts to read some of the works presented in this manner, and frankly, most of them have little inherent value as works of Fiction or Short Story. As a result, I feel that posting numerous stories in a row to gain attention (of whatever kind) should really only receive admonishment. Personally, I note the author or press (if you can call them that) that use these tactics and simply never read any of their articles or authors again.
5. Many writers feel the incessant need to EXPLAIN their story, or otherwise indicate its place in their upcoming novel, or their life. Guess what? A lot of us are interacting with Medium to read your story and perhaps comment on it, or some of us could possibly be from a literary press looking for the next great author. Either way, your bio, what inspired you to write the story, the plans you have for future publications, or what you ate for lunch are of little consequence. Post those on Facebook. If you haven’t written an interesting story, all of this forced presence you’re creating on Medium is not going to endear you to anyone, particularly readers. The Story… The Story… The Story… It’s all about your Story. Any solid creative writing program will teach you that audience is important. You gain audience with consistent writing, not volumes of writing. The words on the screen, or initially on paper (the best way to proof read), are what inspire a lot of us to continue visiting Medium. Whether or not the stories catch our attention, how carefully the stories (sentences, words, images, metaphors, similes) were crafted, whether or not the stories have a hook for readers, and whether or not the author cared enough about their own work to spellcheck their stories before uploading. Personally, after finding three misspelled words in a story I’ve already moved on to the next author on the list.
6. Fiction and Short Stories are about words, not how readily you can find an image online and present it while (in many cases) clearly infringing on websites’, creators’ or photographers’ copyright. Fiction and Short Stories are about how skilled you are at manipulating words and how readily you can draw the reader into a world you’ve created that unfolds before them as they read. Stories with oversized pictures and no intro text whatsoever indicating what the story might be about receive the same treatment from me as stories with more than 2 typos. On to the next story!
7. Lack of comments. A true writer is constantly learning. Learning by reading stories outside their comfort zone in genres with which they are unfamiliar. They discover how other writers can capture an audience or create a simile or metaphor that does the capturing for them. The best way for any writer to grow as a writer is to listen to feedback from other writers, authors, readers, and editors. You cannot work in a vacuum. Very few people comment on stories, pro or con. Lack of comments on Medium are superceded only recently by lack of stories. Every author needs feedback. Every author needs to know how to provide feedback. Every author needs to know how to accept feedback. Feedback is NOT personal. Honest feedback can be positive and negative. Learn from both! It’s all about the Story and only the Story (your Mantra for the day…). Example: More authors than I’d care to mention seem not to know when (or how) to end their story. I’ve read dozens of very good stories on Medium that haven’t reached their full potential because the author tried to tie everything up into a bow in the last paragraph or sentence. That’s where feedback can help. Stories don’t have to present a Unicorns and Rainbows ending. Life, for the most part, simple doesn’t happen that way. Feedback can help authors solidify their opening sentences to draw readership into the story and polish their closing sentences so they resonate within the reader long after the story has ended.

Apologies for rambling on so long Lisa. This was intended as short response to your pointed article about Medium. Apparently the Muse had other ideas.