FFP scopes some reticles get so small @ lower power that they can be lost in the background. Also the reticle gets larger on higher magnification and can cover a small target making it harder for a precise shots.
This is the very reason why many prefer thinner finer reticles on a SFP scopes for long range shooting.
There are draw backs to both FFP and SFP scopes but I prefer the later for the reasons I mentioned.
Here is Falcon Menace 4-14x44mm FFP Tactical Rifle Scope on 14X. You can imagine how large it would be on higher power @ longer ranges on a small target.
Here is the same reticle on 4X