I understand your all words truely but...
Do you remember when the Poloniex was a popular exchange? You could simply see more supply on the sell orders more than circulating supply of an altcoin. Is that all about the numbers they display? If so, how and why they did it?
Of course they won't sell more coins than they have but I meant coins which doesn't exist. They can simply show people only numbers. So an exchance can collect their Bitcoins and they can give them some $ with that way?
The order book on exchange is most commonly from liquidity provider bot. So some of the sell order on the exchange especially those sell order far from the current price is not an actual token. I don't know exactly how there bot works but is the common method of exchange to provide liquidity on there order book.