Yes...that's the point. It will regress to the mean. You will get a central tendency and a standard deviation--statistics. Those statistics can then tell you whether things are performing as desired.
No, you can't. That's why we actually collect statistical data, and do things like Monte Carlo simulations, rather than doing everything analytically. Some math questions cannot be easily answered
...except that it does matter. Because those are the exact questions the designers need to be asking. They need to know the input variables. They need to know the situations. That's how you test things! You're literally saying that because we can't get an analytic answer, no answer is possible. That's wrong! We can get numeric solutions, sometimes very very good ones. That's the whole point of modeling like this. Huge swathes of science today are, quite literally, built upon the back of creating very good computer simulations and then testing novel or unexpected variables to see what happens. That's how we do climate science, since we can't actually solve the differential equations involved and can't do meaningful experiments because we don't have a thousand other Earths to perform experiments on. That's how physicists test models of solar system formation, or the mechanics of how Earth's Moon formed, or literally anything at all involving gravity because the three-body problem does not have general solutions.
Assumptions will go into it. By definition, they must, because some went into the design of the game to begin with. As stated, this requires that you think very carefully about what questions you ask, how you ask them, what data you use to answer them, and whether the data actually supports any conclusions at all (let alone the ones you're looking for.) That's how statistical modeling works.
Just because it's statistical and simulated doesn't mean it's useless. It is exactly the opposite: that it is statistical means we can apply many useful things to it, which can help us seek useful results. Statistics and simulation are powerful tools; like any powerful tool, they must be used with care and diligence.
We're just going to disagree. I don't see the point of continuing on.