Thats not a reason to fudge with the definitions. The existence of sandboxes doesnt mean there are no more pdf exploits. There still are and sandboxes dont mitigate it entirely.
There is also more ways then just turning off your machine. Its needlessly oversimplifying complex topics. Topics that are very interesting and have severe implications. Especially if we are talking about state level espionage.
So in short, no you are wrong. PDF exploits are still a thing. You made unjustified assumptions.
Reading my post it sounds confrontational. Thats not my intent.