You are right about viral load being a factor. You are not right about only macro droplets being a problem. Micro dropplets, that are suspended in air and do not "fall to the ground" soon carry enough of the virus to be infectious in accumulation. This is why indoor areas are problematic regardless of the 6 foot spacing, as the air just gets saturated over time unless you have a continual strong crossdraft.

The smoke analogy is not perfect, as it's composition is less moist, but it is closer to the truth than the '6 foot' model that was itself already a compromise between the now accepted as disproved macro fluid projectile model and economic concerns.