One of the first techniques that a white belt will learn is a hip escape, the foundation of all movements in Jiu-Jitsu. From white to black, it is important for transitions, sweeps, leverage, submissions, you name it. From there, we learn the guard, side control, mount. One of the submissions that we learn early on can be found in any of these positions and white belts seem to latch onto the concept as hard as they latch on for the finish.
The armbar is a submission most found in the white belt world. Seen from most anywhere, it can also be used when an initial submission is failing to work– like the triangle.
Check out some shots of these white belts using the armbar submission to finish their opponents: