Common problem for all boats, all makes.
AFAIK the mold has the DWL established based on the designer's calculations, and this normally is based on a "light load" for displacement. (Notice how perfectly hull #1 floated in the photo session for the brochure... ! )
Owners, by and large, will add gear, spares, personal items, food and drink, and fill the fuel and water tanks... and the boat may well sit lower by an inch or
several inches.
I personally know of several cruisers that had their boat's WL raised by 6 inches or more when preparing to head out. Looked odd when re-launched, and just right when they departed from our little club.... they are in Mexico and new Zealand, respectively, now...
Over 20 years ago I raised the top of the bottom paint from the stock one inch under the boot stripe to about a third of the way up the boot stripe.
A friend with an E-38-200 had his boot stripe repainted, also, and higher by a few inches.
Since owners will really focus on how the boat looks at the original commissioning, I suspect that the builder wants to have it float initially with the boot stripe about an inch above the top of the bottom paint. At that point it's an esthetics and appearance thing.
As the months and years roll by the owner pretty much stops looking at it, but does get irritated by having slime growing above the painted area. Grrrrr....
And then there is the added diaplacement (and lowering of the whole boat a bit) as the bottom slowly soaks up some water, into the outer layer of gel coat. Hundreds of pounds can be added that way on boats the size of ours.
So, I blame it on designing for the visual "honeymoon" phase of initial acquisition, when us owners are dazzled by such details......