Are "Substance Paint" or "ZBrush" sort-of a de-facto must?

So, I saw a finished project and asked him how he made the skin. He replied that he used ZBrush. I was watching a Blender character creation video on YouTube, and he also switched to ZBrush after modelling is done. Is making 3D for free is an illusion and you practically need a ZBrush or Substance Paint?