I think of Fibonacci heaps as essentially just a academic exercise to lower the big-O complexity of Dijkstra's algorithm with very little actual practical use. It always seemed tailor made for that.

Like, Fibonacci heaps guarantee an amortized O(1) "decrease key" operation, which is a stupendously obscure priority queue operation. Except, of course, in Dijkstra's algorithm, where the lowest runtime complexity bounds depends on it.