[cygx]

I agree that it's fair to describe cosmologists as a species of theoretical physicist, given the long standing connection between the observation of heavily bodies and the birth of the modern physical sciences. Still the relation is rather remote.

This is such a weird statement to make.

Let's not forget how we got where we are:

There are two forces active on macroscopic scales, electromagnetism and gravity. At the turn of the previous century, there were some inconsistencies in the way how electromagnetism fit into the rest of physics, which were resolved by the theory of Special Relativity. That shifted the problem to gravity, leading to the theory of General Relativity.

Friedmann then calculated what solutions General Relativity permitted under the assumption of spatial symmetry, the Friedmann models, which form the foundation of the cosmological standard model.

Most of the things I described so far happened before we even had confirmation that other galaxies existed (Friedmann published his 2nd paper in 1924, while Hubble resolved the 'Greate Debate' in 1923 by discovering Cepheids in the 'Andromeda Nebula', nowadays 'Andromeda Galaxy'). That shifted the focus on trying to figure out the model parameters that made Friedmann's model fit reality, and we've been at it ever since.