For a given increase in demand, just how much will the price rise? For a given rise in price, just how much will supply increase? And how long will it take for the supply to increase?
Consider the following:
1. The supply of 1-acre lots in Manhattan, no matter what the price. Ditto for the supply of oil when the existing oil fields are pumping as fast as they can and reserves are running out. Or the supply of passenger pigeons (or other animals hunted to extinction)
2. Even for simpler demands such as apartments, hotels, office space, etc. Just how long does it take to respond to the demand? Even grain such as corn and wheat takes a while to grow.
3. Then there are goods for which the supply simply can't increase: more than one original Mona Lisa? the supply of tickets to a specific concert at a specific venue?
4. And the goods for which the suppliers do not want the supply to increase: fancy restaurants want to stay exclusive; they don't want to grow large enough to let more people in. Ditto for providers of some other luxury goods.
Some over-simplification is inevitable, but why so much when common sense tells you it ain't so?