Just because not everyone goes through each one doesn’t mean they aren’t stages. Not everyone goes to high school, or doesn’t sleep through the night, or catches a ball thrown from a meter away, or has trouble with adolescent relationships; that doesn’t mean those aren’t stages.

“Stages” are entirely theoretical and hotly debated, and you shouldn’t think of them like video game levels where you have to go through all (or even any) of them. Think of them more like theatrical stages: it’s where the action happens for a time, the set upon which the action of your life occurs. You’re almost always going to be on multiple stages at a time, and the people around you are probably going to be on a different set of them.