Earlier quoted context omitted.
I'm I guess what you would call a supply and demand absolutist. There's no "correct" amount of development or "optimal" level of density (wrt prices, I mean; obviously people have preferences ). If you let demand outpace supply, then you should expect the available market-rate housing to increase in price. (And that's true even if you think your city is building a lot, or if you think it's already really dense, or if…
There are limits to how many people land can carry. Vancouver builds up onto a mountain, which is crazy. Yes, for some price, we could terrace the mountain or even remove it. Vancouver is a boom bust town for real estate, now it is in a boom, it will bust eventually, just like it has many times before. There is just too much speculation going on to represent stable demand.
But the San Francisco bay is quite unconstrained, with extremely low population density and massive undeveloped tracts all over. Here, only regulation and laws prevent the cities from becoming bigger.
In general, the vast majority of people live in unconstrained areas, not constrained areas. But because constrained areas are where you get the windfall wealth from housing, people in the physically unconstrained areas clamor to make themselves legally a constrained area by making it illegal for the city to grow out.
So yes, there are limits, but these are political limits, not physical or environmental limits, and they are driven by incumbent owners with dollar signs in their eyes, not concern over nature.