Dark matter/energy (you must know that those are the same by now) has been observed, it is what causes gravitational lensing. The problem is that we don’t know what dark matter/energy is made out of, because there is none near any traditional matter that we are used to. Basically when we look out, something is bending light, so we assume it must have some mass, but we don’t “see” any traditional objects like black holes, stars or planets.
As to the picture you showed, there is no order in there, look at any longer timespans and things are just spinning around, colliding into each other, dying, getting killed and getting born. You just have to look at a black hole and notice none of it is ordered around it.
And the further back you go, the less ordered it gets, the oldest signals, the cosmic background radiation, is just white noise, it is so unordered, we use it as a source for true randomness in cryptography and other computer systems that need randomness.