The point was that stronger lights + ND filters are the preferred method over hypersync. You're intentionally ignoring the first part so you can attack the second. The downsides of hypersync were covered succinctly by GonzoGolf early on. Myself and Thomas Cambell suggested MOHR POWAH coupled with an ND filter. I'm not sure what you don't get here?
Gonzogolf mentioned that HSS could achieve higher shutter speeds, but HSS also lowers the flash power of the flash unit (and is also not found in studio flash units). The Hypersynch mode can also raise shutter speeds to some degree, but bring their own limitations. But ND filters were not mentioned in either context by Gonzogolf.
Tom Campbell was the first to mention ND, "I prefer more power + ND filter to control ambiant with flashes." And that is where it must be made clear that ND will not alter the relative strength of ambient:flash, therefore of no value to the OP question.