Think about all the essays you had to write in school. They'd fill this folder and maybe another one or two. My English teachers pounded certain rules of writing into our heads over and over, and a great many of them stayed with me through the many decades that have passed since those school days.
One of them has been a point of criticism on many things I've subbed to my critique group. I learned that a story/essay needs an opening paragraph that introduces the topic and a closing paragraph that sums up the points made pr pulls everything together nicely.
But time and again, people who have critiqued my work said to dump the opening paragraph and---now here's the biggie--Start with the action. In other words, hook 'em fast. They're absolutely right, and I know it, but old habits stick like glue.
That summing up paragraph at the conclusion works sometimes, but too often we writers want to hit the reader over the head with what the essay contained to make sure they got it. It's far better to leave with a bit of a twist or a surprise statement that is not didactic but still finishes the piece. When the action is over, so is your story.
To return to the opening of a story, consider this. If you use a beginning paragraph to introduce the subject, you run the risk of losing your reader. If you start with a bang, they are more likely to hang on. You're probably thinking But I need to set the scene. or There is background material the reader needs to know. Regarding the scene--forget setting it, pull the reader right into your scene. As for the background material, that can be woven throughout in bits and pieces.
In your closing paragraph, you don't need to state the obvious. Leave the reader satisfied at the end of the action of your creative non-fiction or short story. Stop writing at that point.
If you, like me, were taught to include that opening and closing to help the reader, work on changing your method. I try bu, sometimes, I forget and carry on in the old ways. With a little effort, we can be as up to date as other writers.