Security by obscurity would have made a lot more sense before global communications allowed people to share the results of poking around like this.

Even after the Internet was invented probably 99% or more of users would have no clue about digging into the systems.

I've mentioned this before, but on one of my early contracts I found an 'encryption' function with a keyspace of 32... values. I don't mean 32-bit. The key was prepended as the first byte to the stream, and the decryption function could accept the full 8-bit range.

Fortunately that was replaced by real encryption some time before I left. But I'm pretty sure nobody actually cracked it before then, because I think nobody thought to try it.