Clincher

Imagine reading a pamphlet on the many uses of Nutella. It says at the beginning that it has healing properties, it can boost brain function and it's beneficial to ingest. Well, the author goes on a million different aspects, facets and rabbit trails, and by the time you reach the end of the pamphlet, you have no idea what you were even reading about and what the purpose was. It's like a jar without a bottom in it. You  have to have a clincher to reflect and remind the reader on your beginning topic and arguments. The clincher/conclusion should revisit your thesis, open up new ideas and ultimately, make your reader feel like they're reading a condensed thought. Not a bunch of words smeared on a paper with a common idea! Tie it together. That's why I think the clincher is the most important.