My reasoning for using Shotcut was originally wrought out of desperation. I needed a video-editor that could correct fish-eye effects for free, and other software did not offer the ability to correct for that, weren't free, or didn't fit all my editing needs. Yes, Shotcut did not originally have the ability to correct fish-eye lenses, but I saw that it used the Frei0r effects, and it was an easy fix.
I also use the chromakey every now and then, but the sole purpose I had in mind was the fish-eye correction and some stabilization.
In the future, I hope blender can be used to make overlays that follow points on the screen. Ah, yes, the prospect of having holographic images rendered with actors is too good to pass up.
I hope my reasons help, but it was simply a very selfish reason: I didn't want to pay for a fish-eye lens correcting editing software for making videos.