Without spread, the miss forgiveness is gone. Without spread, the multiple projectile damage is gone. Without spread, the chances of hitting vitals with one shot go down.
If you give up spread, what is the point of going to a tighter group that could partially hit a barrier, break up and produce lots of stray pellets?
But there is a tighter grouping load than Flitecontrol - a slug. In home defense ranges, i.e. less than 10 yards, Flitecontrol is essentially a slug. I've patterned Flitecontrol at 7 yards; the pattern measured 3/4" inch from edge to edge! I did it repeatedly because I couldn't believe it, but it did it every time. I was very impressed until I realized out to 7 yards, I might as well be shooting a slug.
So now here we are using the shotgun essentially as a rifle. Those tight slug-like loads are no more than a rifle shot with low capacity and a lot of recoil.
You seem to be thinking that if you use Flightcontrol, you won't miss. But we know with the stress of a gunfight, with threats that are not standing still, and are shooting at you, we do in fact miss. Add to that subdued lighting, shadows, partially exposed threats, etc.
So if you miss with a Flitecontrol, the projectile is essentially a 1500 ft-lb unified mass of lead out to 10 yards at which point it starts to spread. Or once that unified mass penetrates a an inside and outside wall, it is now 9 pellets with spread and they each have more energy than they would if they had penetrated the walls as individual pellets.