I do feel like there's a historical perspective missing from the article which the GP touches on. Embedded KV stores aren't new (although some of the algorithms behind the current crop certainly are). They used to dominate "backend" software development until their popularity waned as the world got obsessed with "model the domain, damn the computation cost" (because all resources were doubling or more yearly) followed by "we'll just distribute it".
The need for parallelism killed the first approach and the cost of increasingly complex reduce steps killed the second. Now we're back to "how much can we fit in RAM on a local machine" and it turns out, if you can still bang bits for smart key formats, a hell of a lot.
But you're also welcome to write your own post. :)