Question please, it says that jamming these is more difficult. But doesn't that mean it's not impossible, so at some point in the future it could happen?
The cost and scale of disruption matters.
That is true for almost all security. It is not impossible to break cryptography, but it is costly enough as to not be viable in most cases. Most of security is about to make it costly enough to break as to not be worth it.
But yea, calling it inconvenient for most uses is quite an understatement. It did serve many spies well though during the Cold War using numbers stations, even if the Soviets were known to take short cuts by just having a room full of people randomly hitting keyboards rather than using true randomness.