Comment by dzaima

Storing the data in nodes doesn't work if the given structure may need to be in multiple linked lists, which iirc was a concern for the kernel?

And generally I'd imagine it's quite a weird form for data structures for which being in a linked list isn't a core aspect (no clue what specifically the kernel uses, but I could imagine situations where where objects aren't in any linked list for 99% of time, but must be able to be chained in even if there are 0 bytes of free RAM ("Error: cannot free memory because memory is full" is probably not a thing you'd ever want to see)).