Not GP, but if Prolog has been around for 52 years, has many implementations old (SICStus/Quintus, SWI, yap, ciao, xsb, eclipse, many more) and new (Scryer, Quantum, Strawberry, Tau, Trealla, ...) then it follows it's not doing so bad after all.
I have to say the "expert system" quote comes from lack of insight and perhaps outdated CompSci lecture notes when even at the height of "expert systems" around 1990 or before, Prolog's backward-chaining was seen as the opposite of an expert system's forward-chaining.
It may have been the case that what was understood as an "AI language" was anathema following the AI crash around 1988/89 (the original "AI winter").
What also may have contributed to the impression of Prolog becoming less used around 2000-2012 or so is the effect of W3C's/TBL's "Semantic Web" and description logics efforts capturing a portion of the academic and commercial attention in graph and logic databases, as well as in other applied logic domains such as formal verification (in a quite direct sense considering research grants for OWL, etc.)
Early systems were largely closed source, proprietary, licensed commercial systems. In some ways Prolog is 52 years old and in some ways it's 5 years old.
I have to say the "expert system" quote comes from lack of insight and perhaps outdated CompSci lecture notes when even at the height of "expert systems" around 1990 or before, Prolog's backward-chaining was seen as the opposite of an expert system's forward-chaining.
It may have been the case that what was understood as an "AI language" was anathema following the AI crash around 1988/89 (the original "AI winter").
What also may have contributed to the impression of Prolog becoming less used around 2000-2012 or so is the effect of W3C's/TBL's "Semantic Web" and description logics efforts capturing a portion of the academic and commercial attention in graph and logic databases, as well as in other applied logic domains such as formal verification (in a quite direct sense considering research grants for OWL, etc.)