Sigh, no, no, and no. "Textbook" theory is generated by analysis of decades of market data. And yes, miners determine their price ceiling through marginal profit analysis. But you miss two points. First of all, every miner's analysis is different, at least slightly. Differing assumptions, different costs of electricity, differing tolerance of risk, etc. Collate all those price ceilings and you get a gaussian distribution. When the area under the graph equals total supply, you have an equilibrium price. ANY increase in supply results in a lower price.
The second point you miss is that miners, like all businesses, are revenue-limited in expansion rate. If a miner's marginal profit analysis results in a price of $1200/card and you offer him ten thousand cards at only $1100, he doesn't purchase all 10,000 cards. He purchases until he exhausts his funds available for expansion. Can he borrow additional funds? Sure -- but that changes his marginal analysis ... and the more he borrows, the greater his expenses are, and the less profitable the cards become.
As for the ridiculous assertion that, were producers to cut their production in half without impacting prices, I can't believe you seriously meant to suggest something so obviously inaccurate. There are potential purchasers out there willing to pay far higher prices than what scalpers are presently charging. If you cut supply in half, you service a much smaller segment of the bell curve, and prices rise astronomically.