Diego Zamboni has a post that describes how to add a screenshot to an Org buffer. The post considers the problem from the point of view of macOS but is easily adapted to other operating systems. He uses the org-download package, which can take screenshots, but he doesn’t use that feature. Zamboni prefers to take the screenshot from outside Emacs and store it in the clipboard. From there he can use org-download to import in into his document.
I seldom need to put a screenshot in a document and if I did, I’d probably just use org-download in the standard way. Still, I imagine it’s pretty easy to make a case for taking the screenshot outside of Emacs. If you have that use case, Zamboni’s post is a useful way to make things as easy as possible.