I think one can make a short or a long movie without a script.
When I drive around and see a location I can 'see' in my mind what kind of movie you can shoot there. To give you an example:
I was down at the dock where all these fishing boats tied up. It was dark, early evening. I asked a DP and others when they look down there, what kind of story you see?
I suppose many in this business doing their job well, it's planned and they know their craft. However no one could come up with any story or even an idea what to shoot.
I 'saw' a dark story of a smuggling ring as they unloaded the boat. The lighting was perfect and I'd not add more lights and use the dock lights only. It makes it more mysterious and dramatic. Then someone on the shore are watching them. A few close-up shots but not giving away the entire face.
On the spot I could have shot a story without any script, or even a discussion of the story. Position actors and instruct them of the action to take place. In my library there are tons of footage could have been added to the story. I don't like much dialog, it's the best way to shoot and action flick and tell the story.
Yes, anyone can do on the spot story and shoot it. You just need a good imagination and a motivated crew who trust you to make things happen

I know several people who are superb editors and they can take junk shots and make it into a great story. They are not shooters, editors and they know how to do it. There are so many talented people out there who don't have a chance to break in this business... it's a shame.