But even if we just look at the examples given by the parent, most of them are not about systems or models at all. Epidemiology and politics concern practical matters of life. In such matters, life experience will always trump abstract knowledge.
Epidemiology and politics do involve systems, I’m afraid. We can call it “practical” or “human” or “subjective” all we like, but human behaviors exhibit the same patterns when understood from a statistical instead of an individual standpoint.
Epidemiology and politics are pretty much the poster children of systems[0], next to their eldest sibling, economics. Life and experience may trump abstract knowledge dumbly applied, but alone it won't let you reason at larger scales (not that you could collect any actual experience on e.g. pandemics to fuel your intuition here anyway).
A part of learning how to model things as systems is understanding your model doesn't include all the components that affect the system - but it also means learning how to quantify those effects, or at least to estimate upper bounds on their sizes. It's knowing which effects average out at scale (like e.g. free will mostly does, and quite quickly), and which effects can't possibly be strong enough to influence outcome and thus can be excluded, and then to keep track of those that could occasionally spike.
Mathematics and systems-related fields downstream of it provide us with plenty of tools to correctly handle and reason about uncertainty, errors, and even "unknown unknowns". Yes, you can (and should) model your own ignorance as part of the system model.
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[0] - In the most blatant example of this, around February 2020, i.e. in the early days of the COVID-19 pandemic going global, you could quite accurately predict the daily infection stats a week or two ahead by just drawing up an exponential function in Excel and lining it up with the already reported numbers. This relationship held pretty well until governments started messing with numbers and then lockdowns started. This was a simple case because at that stage, the exponential component was overwhelmingly stronger than any more nuanced factor - but identifying which parts of a phenomenon dominate and describing their dynamics is precisely the what learning about systems lets you do.