The same way I'm fairly sure that no-one's ever been attacked by a unicorn. There could be lots of unreported attacks, but I'm pretty sure there aren't any actual ones.
What we do have is millions of actual, real-world attacks (see any security body's top-ten list) that we aren't mitigating because we're too busy focusing on silly attacks that no-one ever uses.
The same way I'm fairly sure that no-one's ever been attacked by a unicorn. There could be lots of unreported attacks, but I'm pretty sure there aren't any actual ones.
What we do have is millions of actual, real-world attacks (see any security body's top-ten list) that we aren't mitigating because we're too busy focusing on silly attacks that no-one ever uses.