Complexity has nothing to do with it. Adult tardigrades are quite complex creatures, far more complex than an adult hookworm, yet the tradigrade can survive dessication and the hookworm can’t.
Just as there is an upper size limit on hibernation at about dog size, so there is an upper limit on dessication at a few millimetres, and he reason is the same: how do you come back.
The first hurdle is how to ensure thereis sufficient water. If an animal the size of a frog were to dessicate then a passing shower will only rehydrate the skin, which then comes back to life before the organs needed to suport it are functional. The skin will then die. Dessication is only avialable option if any wetting event can guarantee the rehydration the entire animal, and that means the animal has to be small.
The second issue is that when an animal dessicates its tissues shrink back fro the point of contact with the environment, and when it rehydrates the tissues swell in the same pattern. Once an animals gets too large it the differential shrinking and swelling will cause the tissues to split. It’s like trying to make a solid clay sphere and sun drying it. It works well for really small spheres, but once the sphere becomes more than an inch or so across the usrface will crack while the interior is still wet.
The third problem is a combination of the other two. If the organism isn’t thoroughly and rapidly dehydrated or rehydrated you end up with osmotic effects moving water or solutes from the surface to the core and vice versa causing cells to rupture or proteins to denature.
So basically dessication will only work for tiny creatures, less than a centimetre or so across the narrowest axis.
I’m guessing some of the nematodes or tardigrades that might get as large as a centimetre.