You did not read what I said, and are inverting the logic. Yes, the Universe manifestly DOES have a few "simple" rules a.k.a. the laws of physics, and HAS produced rocks. But that is literally irrelevant to the point that there is nothing about rocks -- or, if you prefer, the laws of physics and the medium in which they operate -- that appears "designed". The laws are regular mathematical laws and we have no evidence for some sort of highly imaginative "field" of possible mathematical law sets and possible Universal media obeying them that a designer can select from to create the design, let alone evidence for the insane recursion relation in complexity and design implicit on the existence of such a designer.
Any sentient "designer" of a Universe plus their Super-Universe within which it builds the Universe has more complexity (and greater information content) than the Universe that they designed and built. If complexity implies design, then every designer and their Universe must have a still more complex designer in a still more complex Universe. If you wish to assert that this recursion terminates anywhere, so that you can call the designer at that level "God" or "The Master Simulation Programmer", then you no longer assert that complexity necessarily implies a designer, in which case there is no good reason to apply the rule at all even in the first instance without evidence!
Quite aside from this, rocks specifically do not exhibit any of the characteristics we generally associate with designed things, and we have quite detailed mathematical models for the probable history of rocks that do not require or benefit from (in the specific sense of being improved by) any assumption of active design. Neither, frankly, do the laws of physics.
As I pointed out in another thread, the following is a classroom example of incorrect logic:
All men are mortal.
My dog is mortal.
Therefore, my dog is a man.
All computational simulations are discretized.
The Universe is discretized (or not, see other replies).
Therefore, the Universe is a simulation.
You argument is even worse:
Rocks, that do not appear to be designed, can be designed anyway.
Therefore, we can never say that rocks do not appear to be designed.
My dog, that does not appear to be immortal, might be immortal anyway.
Therefore we can never say that dogs are mortal.
Sure we can. What you might get away with is the assertion that there is a very small chance that some living dog (including my currently living dog, that isn't dead yet!) might turn out to be immortal. However, every single dog since wolves came out of the cold that was born more than thirty years ago is to the very best of our observational knowledge and theoretical knowledge of dog biology dead as a doorknob and every living dog that any of us have ever seen appears to be aging and we all understand how aging and disease and accidents all limit life. To assert immortal dogs you have to just make stuff up -- invent things like "dog heaven" where all dead dogs run free and have an unlimited supply of bones, or imagine that somewhere there might be a very lucky ex-wolf that failed to inherit an aging gene and that has never had a fatal disease or a fatal accident and that somehow has eluded our observational detection -- so far -- and (ignoring the second law of thermodynamics and the probable future evolution of the Universe based on the laws of physics) assume that that dog will somehow survive longer than the Universe itself probably will. Both of which are pretty absurd.
So I repeat, there is absolutely nothing about rocks that makes us think that they are designed. That does not imply that they might not be designed after all, it is not a logical statement that rocks could not have been designed, it is an empirical statement that, just as dogs appear to be mortal (and not humans, however easy it is for dogs to make the mistake, especially around dinner time:-), rocks appear not to be designed. When I find a rock on the ground as I walk along, I do not quickly look around trying to figure out who designed the rock because it looks so very much like a made thing. Quite the opposite. And, I can almost guarantee, so do you!