"I just use an array" doesn't solve the problem "What if the array is full?". In fact it makes that problem acute. A linked list structure will degrade gradual

"I just use an array" doesn't solve the problem "What if the array is full?". In fact it makes that problem acute. A linked list structure will degrade gradually as we shove more entries with the same hash into it, every look-up incurs a pointer chase down the entire list, slower is eventually unacceptable but we do get signs first -- but with arrays we're just screwed, in C it's pretty likely we end up with an illegal dereference or we lose data once there's no room.