I'll admit my experience is more with vineyard than orchards, but at least for grape, this isn't true. You only cut down old, unproductive vines, and market demand is not a factor. You never know how much you will produce YoY, so basically you try to only produce what your domain can handle. (The english translation for the following will be rough i realize).
On the "planting" side, you're wrong: a limited stock of "rootstock" (if this is the correct translation of "porte-greffe") is produced each year. As those are specific to a certain type of soil and take time to grow, you don't produce a ton each year. And vines "rootstock" are _a lot_ easier to grow than other trees (you have a mother-vine that you don't prune, you bury its branch in the soil, and over a year it will develop roots). My guess is that for orchards, your rootstock should take 3-4 years, so it isn't that easy.