Frank,
Although, highly unlikely, a scenario like this could happen:
A, 2/10, B-15, A=14, B=21, 0:07 (4), A has exhausted their times out. A11 takes the snap and advances to the B-10, where he is surrounded by opponents, and his tackle at that point is imminent. Although he may know it will be a foul and a penalty, A11 throws the ball forward into the ground, for an incomplete forward pass. The game clock is stopped for the incomplete pass and to complete the penalty for the illegal forward pass, with 0:02 on the game clock.
Without the 10-second subtraction (which also means the clock would start on the referee's signal) Team A would be able to run another play, effectively, gaining an extra "time out." But, with the 10-second subtraction, the game is over, negating the unfair game clock tactic.
Other scenarios can be presented that still leave some time on the game clock, and the game would continue, but only after subtracting 10 valuable seconds from the game clock, and starting the game clock on the Referee's signal. Also, if, after the 10-second subtraction, the game clock is at 0:02 or 0:01, Team will not be able to "spike" the ball to stop the clock. Sadly, with a score differential of 3 or less, Team A might be able to use the administrative interruption to get their field goal team in place while the penalty is being completed, and then kick the game winning field goal, even with just 1 second on the game clock when the Referee's signals to start the clock. That doesn't seem entirely fair, either. But "them's the rules" as we say in West Texas.
But, that would take a really, really smart and aware player to pull that off. Like, say, Tom Brady....