Even if you argue that TL is experienced from 1kt to 150kts, there is a big gain in rotor thrust as the helicopter flies clear of its vortices. That happens at 4ft and at 200ft. What is missing at 200ft is ground effect, which gives a further performance advantage by allowing you to hover near the ground with a lower collective setting. If you set up for an OGE hover in nil wind (a lot higher than 200ft AGL if SE) you will fly back into the vortices and experience the same burble. Then if you muck up applying enough power to maintain the hover, you will experience another burble as you accelerate into incipient VRS.