And what pray tell except for heuristics is the list of children used for?
I could find a use in the scheduler (oldest_child and younger/older_sibling).
I could find a use in mm/oom_kill.
I could find a use in irixsig where it roles it's own version of wait4.
Perhaps I was blind but that was about it.
I didn't see the child list implementing any semantics we really care
about to user space.