The “security” came from the fact it was tuned to receive a specific frequency. Earlier radios were not very selective on which frequencies they would accept.
The main benefit was not actually security but a reduction in congestion. Spewing interference out randomly is not an efficient use of airwaves.
Except that the one in the demo wasn't, enabling the hack:
It was discovered that the receiver that Fleming had been using was not, in the phrasing of the time, syntonic. It wasn’t tuned to a specific frequency, excluding all others, because a syntonic receiver would have been too large to use in the demo.
I think I read somewhere that English language legal settings have a history of a peculiar dialect of French mixed in, owing to the Norman history in Britain.
Norman, and Napoleon. The landed aristocracy has moved back and forth across the channel for a thousand years. They also fought countless wars against, and a couple alongside, each other. That creates a common culture that bleeds into all language. It happened in law, but also greatly in medicine and other sciences.
The main benefit was not actually security but a reduction in congestion. Spewing interference out randomly is not an efficient use of airwaves.