Mr. Argumentor
I fab shitboxes and shitbox accessories.
The parking brake exists so that you're not putting all of the vehicle's weight on the transmission. It's not just a wear issue but a safety issue. Not using the parking brake means there is a single point of failure in keeping the vehicle in place.
Nowhere near that big of an issue as it is nowhere near the entire weight of the vehicle resting on the parking sprag. If you live in San Fran you would do well to use the parking brake, but most people don't live there.
Besides that, the possibility of a vehicle having a worn or poorly adjusted parking brake far outweighs the possibility of a vehicle having a bad parking sprag.