In his 1975 paper, Circumstellar absorption lines and mass loss from red giants, Reimers gave a relation for mass loss from red giants via stellar winds as $$\dot{M}\propto\frac{L}{gR}$$ where $\dot{M}$ is mass loss, $L$ is luminosity, $g$ is the acceleration due to gravity at the surface of the star and $R$ is the radius of the star.
Reimers wrote that this was "the simplest quantity" based on the three parameters that had the units of g s-1.
Using observational data, Reimers was able to determine a coefficient, $\eta$ that created the law the bears his name. However, assuming I'm understanding the paper correctly, he seems to have chosen it as an approximation, just because it was simple and it worked.
Did Reimers have any theoretical evidence for believing that the law took the form it did, or was this assumption simply based on a conjecture?