Here's my nickel's worth. From everything I've seen or read, no real big time pro's, including Aaron Martens, uses the FG knot. It takes too long to tie out on the water and brings nothing to the goal of catching fish. I've watched Youtube videos of all the PB's that claim they use it. I can tie a half dozen Alberto or Uni to Uni knots in the time they take to tie a FG knot, and you know they edited the snot out of their videos.
If guys that fish for a living can't find a reason, I darn sure can't.
Catching fish is the goal. If it don't support the goal, I don't need it. I ain't here to brag about the PB knots I tie.
PS: PB=Phony Baloney