Yes, but the software stacks aren't the popular choice because the programmers are new, it is because the programmers want to be seen as "not new" within 2 year

Yes, but the software stacks aren't the popular choice because the programmers are new, it is because the programmers want to be seen as "not new" within 2 years, there is a heavy selection bias for very driven programmers to become senior programmers by their second year of experience, because they are experienced in the popular new shiny thing. That's the causation behind the correlation, by being not easily replaceable, and commanding a high premium for their time faster because of it. Sometimes there is actual utility in knowing that newer stack, sometimes.