The Akademiya banned books and controlled access through the Akasha because Sumeru is a real place with centuries of real history. It would be impossible for them to cover every single piece of evidence of what was there before, and so the sages relied on people's complacency to trap them in an informational bubble. To not only remove every piece of information, but replace it with blank props? That's extrenuous if the point is to hide what came before.

[He waves his hand out before folding his arms.] Someone out there is trying to control at least the population here now. Cages may be designed to look like the natural world, but they're still artifical bars for keeping things in. The Akasha was also used to trap the people of Sumeru in a recurring dream after all, if we're drawing comparisons.

[What seems inexplicable as a quirk of this place starts to make more sense if it's not actually a city at all, but a set piece.]