There are several long-winded threads on this topic in the archives.
This is one such animal.
For those interested in the sort of boundary layer under consideration, the standard equation used for steady wind variation (without obstructions to do silly things) is the standard 1/7th power law used for flight test and often graphed in the AFM performance section.
v1/v1 = (h1/h2)^(1/7)
A quiick plot of speed by height will show where the consideration becomes important - around the 300ft mark.
The reason one is exhorted to bleed off this additive is that the profile is reasonably predictable. Gusts, on the other hand, are rather random and there is no basis for trying to fiddle with them in the middle of late final and the flare to touchdown .. the better risk management approach is to use the 1.67 factor as a risk mitigator for the higher touchdown speed.