I’ll chime in, and give a hobbyist perspective
(And I’ll add that this is my first post in a couple years, life intervened but has let up for the moment:))
As a Jack of all trades (and master of none) I got into Arduinos a decade ago without a specific use, but as the saying goes when holding a hammer every problem looks like a nail, I found uses in many of my other hobbies. Plus they’re neato. I used to build solid state Tesla coils, and dabbled in holography for example.
As an exercise I cobbled up a brushless motor and was using the micro to do the commutation. This led me down the path of seeing how fast I could switch, and I learned about bit-banging, as “digitalWrite” was hopelessly slow. I soon reached the limit of what the chip could do, which while reasonably fast, completely consumed the chips capabilities. That’s when I found out about FPGAs, and suddenly many of my nails needed a new hammer 
So basically the parallelism and speed is what I’m interested in. I haven’t done much yet, and un-learning the sequential mindset that has defined all of the programming I’ve ever learned has been a challenge, but once I started messing around the possibilities are exciting.
I doubt my uses will become as complex as vintage machine emulation or video processing, but when I was making holograms I built an analog PID controller for a fringe-locking mechanism, and could have def. used an FPGA. Arduino was abandoned early on, not nearly responsive enough.
Hope that adds to the story
Wells
