What they are really wondering is how the objects IN the solar system formed. Well, they are all stages to a single star's evolution. Some are more evolved than others. Some are even broken up parts to ancient stars which give the appearance of being worlds themselves, such as asteroids and small moons.
They all have timelines mutually exclusive of each other. The fact that they are in their current arrangement is random. To drive the point home, there are two main philosophies here which people are unaware of.
1. The solar system is a single object.
2. The solar system is a bunch of objects all mixed together randomly. (systems inside of systems)
Which do you think is the sound philosophy?
What really happens is that all this boils down to basic communication problems. When a scientist says, "solar system" they think "one", or "singular", thus any explanation of the singular system will need a singular process.
If they think multiple objects, then they will lean more towards explaining what the objects are doing, absent any notion of them being parts to a larger process. They are not parts to a larger process, the orbits are not processes which formed them, and that is the only thing that relates them. Take the orbits away, and what do you have? Singular stars in distinct stages of evolution.