Weren’t the 70’s quite inflationary? Tricky Dick closed the gold window in ‘71. I think the higher interest rates is what made dollars more expensive for financing projects of all kinds including smut. The artificially low rates of recent decades made financing cheap for anything including, again, smut.
Discussion
Yes, the late 70’s saw rising interest rates, topping off in the early 80’s.
Regarding my rigorous nostrian economics: I’ve done the analysis and it’s simply undeniable that the porn industry was indeed still benefiting from the gold peg.