Why not - if I learned it I wouldn't have had this run on sentence issue I currently have.
I imagine this diagraming is a tool (not an end all) for this reason - I can see how it would break a sentence down to help you avoid it.
There's nothing at all wrong with run on sentences, Linkat. We speak in run on sentences and when we write, save for those infrequent times when you have to pound out an academic paper, .. have you finished yours yet?, we write as we speak. It's perfectly natural, that's why, with the advent of the internet, the shortcuts that we don't normally use in academic/formal writing, are proliferating.
Children should initially write as they damn well please, in the sense that they should write just to become comfortable with writing. Then after they have written and written and written some more, we can take one piece of their writing and show and tell them that though this is perfectly fine for the vast majority of instances, the odd time, we have to make some changes to meet writing for academic purposes.
Then we can show/tell them that we also have writing that is similar, but not as formal in nature as academic writing and that is, we'll call it newspaper writing
Kids have to learn that there isn't just one kind of writing. They have to learn that writing as we speak isn't bad, it isn't wrong. If it was, then how could anyone ever write a novel? Should all direct speech within a novel be edited to meet the strictures of formal writing? Of course that's nonsensical.
The reason that kids have to/should learn all this is so that they don't grow up thinking that they have a problem with run on sentences.
Sentencing diagraming also isn't a memorizing exercise - it is a logical one.
That's true. I was referring to other aspects of language teaching. But because it's taught with these other phony aspects of language, it becomes, ... , ... what's the word I want, tainted by the nonsense.