If you went back 400 years and demanded that physicists explain my dog's behaviors, you would probably get some answers that sounded OK (kind of like Aristotle's attempts at physics) and maybe even were convincing to people of the time, but they wouldn't have much truth value. Present day economics has a few equivalents to Boyle's gas law, many equivalents to ancient Greek physics, and no equivalents to atomic theory.
The "true market" is like "no true Scotsman" or "a closed system" or "a spherical cow on a frictionless plane". It assumes something that doesn't exist. In economics the influence of the things it assumes wrongly can be very significant. In physics wrong assumptions can also make the results wrong and a lot of work (or rather most work) is done on checking if all the assumptions are sound and ensuring that the influence of the remaining gaps are negligible. That is something that is hard to do in economics when it involves interactions with the global market.
Yes, special theories can be precursors for more general theories.
Come on, what is physics about then? ;)
Even today, systems like my dog are computationally infeasible to predict from the fundamentals, even though everything my dog does is a logical consequence of QED. That's why it is impossible to make progress without assuming a spherical cow and then traveling to every dairy farm in the world in search of the roundest heifer available.
In 400 years economists might still be unable to predict recessions, but I think by then the specific and very true theories of today will have had enough time to evolve into general laws that could predict recessions in principle.
To some extent this is also true for the economy which contains many feedback loops and meta-stable states. Even if we have the perfect theory it might still behave chaotically and might be as unpredictable as the weather.