[@Raineh Daze]
I know of that, you might also know I brought up king solomon  which was a more important example since he was on the turning point of the age of gods and age of man.

The worlds foundation was entirely changed by its dominant species being man. Changing the foundation from Mystery to Physics is what lead to the phantasmal species leaving the world. As we know. Mystery is in decline because the foundation of the world shifted. Mages now are incapable of performing 'magic' and are stuck with mage craft due to mystery being a fraction of what it was.

Showing magic to the world whoms very foundation is antithetical to mystery would be the equivalent of spreading mystery too thin making it nearly useless. 
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Disregarding human nature. Disregarding issues with the melting pot of servants. Disregarding even the fact that certain servants are naturally antithetical to eachother. Revealing Magecraft to the entire world is a detriment to the art. Since if we agree that mystery is a limited supply.

We must remember that Shirou emiya for some goddamn reason could use his nervous system as a means to use magecraft (He literally thought he had to create magic circuits whenever he used the art). He wasn't using his natural circuits at this time. He had turned his nerves into a means to cast magic. Meaning if Shirou, the 'average' boy can do that. What is to stop, hundreds or thousands of people from doing that. Which would draw heavily on mysteries supply. 

Magecraft becomes common knowledge - Kiritsugus basic teaching method would likely be replicable by other mages, also common knowledge - A person with no knowledge in magecraft learns it the wrong way like Shirou did.

Suddenly you'll have new familys popping up that discovered their natural circuits or people turning their nerves into circuits (dangerous but possible)

Mystery spreads too thin in this scenario also.

TLDR: The World of Fate/ fails into a complete and utter poltiical and mechanical mess when we apply real-world logic to it (Which I seem like a complete and utter fool for doing so I admit). So for the sake of everyone I'm just going to stop and just go with the flow.

This was at least a insightful look into this worlds workings at least for me at least. So thanks everyone.