I appreciate those explanations, but the confusion or obfuscation about "infinite economic growth" has to do with the neoclassical economist's attempt to make economics seem scientific by making economic discourse sound like that of physicists, as Philip Mirowski explained. So just as physicists abstract away from particulars, focusing on structural, mathematical relationships in physical systems, theses economists sought to do the same for economies. Thus, as I said, they abstracted from psychology, biology, climate sciences, and so on.

"Neoclassical growth theory is an economic theory that outlines how a steady economic growth rate results from a combination of three driving forces—labor, capital, and technology. The National Bureau of Economic Research names Robert Solow and Trevor Swan as having the credit of developing and introducing the model of long-run economic growth in 1956. The model first considered exogenous population increases to set the growth rate but, in 1957, Solow incorporated technology change into the model."

The appeal to technology there, as reflected in that Investopedia article, may be interpreted as an appeal to what you call "intensive growth," or to an increase in efficiency. The bet is that technology makes things more efficient.

Crucially, though, that talk of indefinite intensive growth looks a lot more like a reckless gamble than any kind of law arising out of an understanding of technology's benefits and drawbacks. By making things more efficient for cocky primates, aren't you making it easier for humans to destroy themselves and the planet's ability to support life? That's the foolishness of focusing on technology while ignoring psychology, biology, philosophy, etc. The economic concept of efficiency is far too narrow to be non-propagandistic.

Also, "intensive growth" is obfuscatory since the increase here isn't really growth at all but an increase in the measure of efficiency. That's like saying you keep growing as you get older, so the elderly are larger than they were when they were middle aged. No, their years increase, but that's "growth" only in a misleading, metaphorical sense. So it looks like orthodox economists may want to shift ground from extensive to intensive "growth" because they don't like admitting they're ever wrong or that their initial boasts about endless economic growth were propagandistic rather than scientific.

https://www.investopedia.com/terms/n/neoclassical-growth-theory.asp