Due to the way Prolog backtracks to find a final solution, it can be increadibly slow, and it has to be able to 'undo' an operation. On top of that, from what

Due to the way Prolog backtracks to find a final solution, it can be increadibly slow, and it has to be able to 'undo' an operation. On top of that, from what I recall, it's pretty easy to have the backtracking to stumble into an infinite loop. As leaky abstractions go, that's pretty severe, probably enough to make people question the abstraction's usefulness.