Pulling them out of my ass, mostly. Like, the people I know in the field don't seem overly worried, but my own opinion mostly comes from a general awareness that stuff in LEO comes down eventually, and that for the orbit the Starlink Stuff is on, that would probably mean a few years max.

Not my field, and if I actually research it, I might find I'm wrong.

I still maintain that even a complete loss of launch and orbital capability, while of course a great and horrible disaster, wouldn't doom us much more than our current course as a species already is.

Right. I'll note, that your linked article says nothing about Kessler beyond a quote of his saying that space debris would continue to increase even if all launches stopped. Otherwise, the article mainly comments that the sheer number of Starlink satellites below the ISS could interfere with launch/entry opportunities while drastically increasing the number of space objects being tracked by the DoD and NASA.

There are plenty of legitimate reasons to criticize Starlink, all I'm pointing out is that Kessler Syndrome is not one of them. I'm assuming you've somewhat ironically blocked me, but since we're exchanging links, here is an article that interviews several scientists including one that worked under Kessler at NASA and now works on NASA's orbital debris modeling.

https://aerospaceamerica.aiaa.org/features/understanding-the-misunderstood-kessler-syndrome/