Yes, I have even been an instructor for some of these classes. No, knowing how to take a limit / apply steepest descent does not tell you whether your model of reality is correct, it just lets you convert your model (quantum) to a more restricted model (classical). But you do not know if your intial model is not itself the limit of another model.
Converting the quantum model into a classical model as the limit is taken of greater distances is an explanation of why we don't see quantum mechanics in our daily lives. It shows that no extra dynamics are necessary to "kill" quantum effects on macroscopic scales, because within the laws of quantum mechanics, it is already explained.
Decoherence theory explains that if you have an entangled system that is not sufficiently isolated it will pull in the environment (including the researchers) quickly into the superposition. This explains why a human won't see a "blur" or whatever if you look at Schrödingers Cat. But this seems apparent from the start unless you subscribe to the Copenhagen interpretation literally (something I'm pretty sure not even most of the earliest QM researchers did).
Since decoherence is just a linear (normal) process in the linear QM realm, you still need to postulate the Born rule and subscribe to one of the interpretations thereof, even if you're an Everettian, to make predictions. I think this is the main open ended question in QM..
But sure, there are many fringe theories going around and doing tests to falsify them would be good, it just seems steep to do it at $1B and the experiment only pushes the limit quantitatively, not qualitatively (as the same experiments are done on Earth regularly with lighter objects).
