This is the correct analysis: organized crime already existed fully formed by 1920. What it did was shift energy to booze from gaming and prostitution.
The evidence is that it did not “appear” and was not “caused” by Prohibition, but that Prohibition was a better money maker than its other operations.
We cover this at length, especially in the notes, in “Patriot’s History of the United States.”
Which is exactly the problem with all prohibitions - they're easy money for violent criminals.