Club Of Rome Defense;
As I remember it ( for I was there) The Club of Rome authors of "The Limits to Growth" clearly stated their model was an approximation and the projections were wide crude estimates, They weren't so much doom mongers as some of the utra-greenies of the time were, but they were capitalist business people looking at possible future scenarios.
In the opening pages they had two interesting concepts..
1) A scattergram showing peoples attitude to events, the future and it's impacts on them. One axis was time and the other was 'distance form the event' Not surpisingly the points congregated around soon and nearby. Obvious really, but worth describing.
2) The concept of "Indian Equivalents" or IE. That is the per capita consumption of the average Indian citizen back in the 70's. Given this base the consumption levels of individuals in other nations could be expressed in IE units. This allowed a standardised economic consumption population to be calculated for the planet It also allowed for growth to increase the value of a persons IE value combining physical population growth with economic growth giving a net figure. (I have no idea how those 70s IE numbers translate to today.)
Although your article points out that the changing prices of resources will alter the amounts of materials that can be extracted or recycled there are a few things that are finite.
A simple calculation of available land goes as follows.
The Earths surface area 510 million sqkm of which only 1/3 is land between 7 billion people
Gives each of us about 20,000 m2 each or a circle of ground about 160 m in diameter surrounded by a circle sea about 70 m wide. From that we extract and grow everything we need to sustain life and lifestyle Food,water, minerals, energy, entertainment, waste dumping etc.
BTW when I was a lad my personal island was about 250m in diameter. How big will it be when my 9year old grandson is my age..