> One other advantage of intrusive data structures is the ability to link a payload into several parallel collections without indirections

My example here from the top of my head are intrusive heaps, which are provide a neat way of implementing A*. Here you combine a HashMap and a Heap (over a Vec) where the Heap has the data, and the HashMap maps SearchNodeId to Heap indices. This allows O(1) lookups by search node Id into the Heap (as opposed to a linear scan) despite elements in the heap being constantly shuffled around as search nodes enter and leave the heap.

I'm sure that using HashMaps as a parallel index to other collections can be useful in other scenarios, but I don't know if combination of other data structures works this well, the synchronisation cost might not be worth it.