Get off of my timeline

Twitter is a never-ending source of language peeving. Lately, a twitter user expressed eagerness to see the 'correct' use of off of. Well, joke's on her because there is no correct use. 

Regular readers will know that this is a linguistics blog, and as such, we're not in the business of dictating correct usage, preferring instead to document and ponder upon usage such as we find it. I wouldn't normally say that there's no correct use, because normally we'd be contrasting standard and non-standard uses and I'd be pointing out that both are valid in their respective contexts. 

The standard equivalent of off of is just off, as you are surely aware. Merriam-Webster says 

The of is often criticized as superfluous, a comment that is irrelevant because off of is an idiom. 

Which is pleasingly snarky, I think. 

Our friend the twitter user responded to all the many people who helpfully gave her examples of off of used in a phrase (such as the Rolling Stones' lyric Hey, you, get off of my cloud) by asking what of is doing - what does it mean, what does it contribute? 

Answer: nothing, just like it always doesn't. Lazy of, never contributing any meaning. 

Off of is a preposition (not two prepositions, as it looks like, because it doesn't have two separate bits of prepositional meaning). Or if you like it's an adverb and a preposition - I don't really like but it works as follows. Compare it with on and on to: We drove on (=We continued on our journey) and We drove on to Peterborough (=We drove further until we reached Peterborough). Now to is linking up the verb with the object Peterborough, indicating movement towards it, and on adverbishly indicates continuation of the action. On to can be contrasted with onto like so: We drove on to Peterborough (=We drove on until we got to Peterborough) vs We drove onto the ramp for the ferry, where onto indicates movement to the top surface and doesn't at all mean the same thing as We drove on until we got to the ramp for the ferry. 

There's no comparable difference for off and off of that I can think of. Hey you, get off my cloud works just as well sentence-wise, if not scansion-wise. And helpfully we do the opposite with out/out of: in Standard British English, at least, you would say get out of the house, not get out the house, but both are used and there is literally no reason for the pattern being the opposite way round. I told you. Of is a great word but it's contrary and wilful.