Disagree. I use holds on 3-6 x on my SWFA 3-9 and have shot at over 1000 yards without cranking it up all the way.IMO the FFP argument is lost when the top end is only around 10x, and maybe upto 12x. If I'm needing a true reticle for holds I'll already be at 10x.
Now when you start getting higher power then it's more important. The highest magnification I've shot at game with my NX8 2.5-20 was around 9x. Using enough magnification to shoot, but keeping a max FOV.
IMO, any argument for more than 10x is lost when it comes to field shooting. Holds remain useful at all magnifications though.
I also think a fixed 4x is a great hunting scope for all realistic ranges (out to 600ish yards). High magnification is nice punching paper though.