An incident meter actually should be influenced by the white sand beach, because there's a lot more reflected light in that situation from the sand and the water than in most sunny scenes. If you look at, say, they old exposure guide they used to print on the instruction sheet they used to include in the box with a roll of film when film always came in a box, and oh, those yellow painted metal canisters...okay, I'm getting too nostalgic--anyway, the graphic would generally recommend stopping down to "sunny 22" for a sunny day at the beach, because there really is more light there. It is like the difference between photographing in a small studio with bright white walls vs. a large studio with high ceilings and black curtains along the walls to absorb stray light.
But in more typical lighting, yes, the advantage of an incident meter is that it isn't affected by the reflectivity of the objects in the scene. This makes it good for studio use, where you can control the contrast ratio of the light and the general level of the lighting. Incident metering in available light involves more awareness of the contrast of the light and the reflectivity of the objects in the scene, and whether it is possible to read the same light as the subject, which can be quite distant from the camera in the case of landscape photography. BTZS is an approach that adapts incident metering to the field.