That's my hypothesis for why logic-programming's popularity faded somewhat from its initial promise. When it was new, it was one of the few widely available ways of doing declarative programming, and contrasted strongly with procedural programming. But in the years since, lots of other declarative approaches have chipped away at the monopoly of logic programming proper over declarative approaches to programming.

I wrote a bit about that here: http://www.kmjn.org/notes/prolog_lost_steam.html