[@Raineh Daze]

The Age of Gods is directly tied to an abundance of 'Mystery'

The Age of man is literally a result of mystery's decline. Where magic and mysticism is now replaced with technology and Science, The Death of king solomon for instance accelerated the decline of mystery.

Even in the modern era mystery is slowly and inevitably dying out as science develops as the worlds foundation is now on physics, there is a reason why Mages are trying to recover what was once possible in the past. 

The greatest example of mystery against science is reinforcement being unable to work on a firearm. It is simply impossible to reinforce a firearm with magic due to the fact that the firearm rejects mystery due to being a complex mechanism of science

This means that Mystery = Magic remains true as Mystery is the fundamental power that powers magecraft which even then is inferior to the magics of old because of the decline in mystery. 

Thus, it is wholly likely that the moment you make magecraft common knowledge any mystery it would hold would rapidly decline. Because common knowledge and understanding is a detriment to mystery's existence. 

Lets take a look at another Noble phantasm for evidence, Since they are in this RP. Thomas Edisons WFD, exists to erode mystery itself which is why it is an anti-populace NP. Since it shows the technology of man performing things that were once only possible with magic.

Again this could all be handwaved away if that Chaldea used that massive stockpile of grails they somehow acquired or if someone won a the fuyuki holy grail war. And simply wished the world to be this way. Which is what happened in reqieum. 

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the TLDR is that if it were to exist in this capacity. People would make their own summoning systems since all goverments would want a piece of the pie they'd likely round up their mages to get working on a system.

Im just saying that logically without even bringing up that such a high concentration of heroic spirits would cause Alaya and Gaia to have a seizure 

Also in fate requieum, the plot hook is that the protag summons the last servant into the world. 'I'm a death god - my job is to kill Servants." The girl who was separated from paradise meets the final Servant summoned in the world'

So it seems that even in reqieum there is such a thing as going too far.


Humanity is known for not taking things sitting down, lets say you built a superweapon tomorrow that lets you destroy the world, you either become a tyrant suppressing rebellion or watch as someone else build the same superweapon or destroys yours.


Final point: 
Just give a working explanation for why this massive reveal isn't causing a huge decline in mystery. Or just say its a grail wish. Both work!