Free floating and barrel vibration are two distinctly different things that can affect accuracy.
A free float doesn't improve accuracy at all - it minimizes the shooter moving the point of aim. Eliminate the uneven stress that is never applied consistently, and the barrel shoots to it's point of aim. What creates the dispersion as a group is caused by other factors. Given it has the perfect theoretical ammo that has exactly the same grain weight, powder charge, ignition burn, and engagement in the rifling, then barrel vibration is more clear. As the bullet passes down the barrel, the peak powder charge and expansion under diminishing pressure causes the barrel to vibrate - which means the muzzle is moving back and forth at a fairly high rate.
Where it is when the bullet exits can vary a lot. Precision target barrel makers tend to cut their barrels at a node point, where the muzzle isn't moving much at all. Others add dampening weights at precise locations to minimize it.
As said, you could free float a barrel, and the vibrations will actually make things worse. What is important is to have an accurate barrel to begin with, precisely loaded ammo, and the knowhow to make it shoot to it's inherent minimum group. Not just slapping answers onto a gun that hasn't demonstrated the need.