Any frame, however slim, tells the eye exactly where the whiteboard ends and the wall begins. That boundary is useful for a functional object but works against a room trying to feel calm and continuous, since it introduces a hard edge exactly where the wall would otherwise read as one uninterrupted surface.
Removing that boundary does not make the whiteboard disappear. It changes how the eye processes the wall as a whole, treating it as one continuous plane rather than a wall with an object attached to it.
Designers sometimes describe this as the difference between a wall with an object on it and a wall that simply does more than one thing, which is a useful way to think about what removing the frame actually changes.
Interior photographers who shoot completed office fit-outs often note the same thing anecdotally: rooms with fewer visible object boundaries tend to photograph as calmer and more spacious, even when the actual floor area is identical to a more visually broken-up room.