The Quest works because it is a standalone device. You don't have to plug anything into the unit, you don't have to have wires everywhere, and you don't have a significant risk smashing the unit to the floor because you literally can't see where the cables are, what they're snagging on, etc.

Meanwhile, conventional VR setups get around this by the PC being heavier than a handheld, as well as possibly by being situated under the desks. Laptops are less risk still than a SD, because the former is still heavier than a Nintendo Switch and is made to be used on a desk, with rubber feet for grip, something the SD form factor doesn't have

That and the conventional use case for the SD is fundamentally incompatible from a user experience perspective. It's a mess of cables, and most VR software requires more physics space to operate than you would realistically have in a non-home environment.