Presumably Brew Kits are created with a calculator ?
The Original Gravity (OG) in combination with the chosen yeast makes the product ?
Most LME’s are hopped, most DME’s are un-hopped, using both to dial in the correct IBU.
It might be all about marketing…?
Ask Mr Ian Williams, he might tell you his secret, how he is choosing his LME / DME combo.
DME has more fermentables, because it’s more concentrated, hence one uses less.
Adding the correct amount of DME to the water won’t change clarification.
Measure the OG and you’re ready to go.
I have used both as a single addition, and can’t see any difference in clarification.
Be aware, that some yeast’s Flocculate better than others.