The link helps with the stock set-up because the stock shock is completely over-sprung and the link alters the rising rate of the swingarm which requires more spring rate for the same weight.
Even Max from Traxxion, whom I have feuded with for years even though I actually like the guy, used to claim he had a bucket of these links from RC51's at his shop because he couldn't get them to work right with a Penske shock. At the time I thought he was just baggin on the link because it was one of Dan Kyle's major selling points with the Ohlins shock, but as time went on myself and many others I trust had similar results.
Now if others want to argue my findings then so be it. I'm too tired and apathetic about an 11 year old bike to really argue with them, but I have been proven right on all things RC51 for years and I doubt too many people that are saying I am wrong have been employed to test and develop bike parts over the years as I have. When I tell people something works it does and when I say something doesn't it doesn't. I don't subscribe to the placebo effect or need to read a bunch of magazines to form an opinion. Consistent lap times and astute observation of the bike dictate my responses not conjecture.
