It's a progression.

To achieve simplicity, you must first outline the complex process, identify commonalities, and then simplify.

You can't reach simplicity without going through and organizing our messy, internal thoughts.

Yeah this exactly.

Simplicity is borne out of messy, complex stuff. That one then has to do the work of removing the stuff that doesnt matter / rethinking how stuff fits together.

Most people dont really have the mental energy or discipline to go through this process, so by on large, complexity exists in the world.