Actually that isn't correct. A bicycle is a distance amplification machine at the expense of torque. The bike travels further than your feet do even in very low gears.
Even if the chain broke first it would continue to follow through the stroke until it reached it's last link as a single unit.
That's not true either. A popped pin or bent side plate could easily get jammed into the adjacent cogs and do all kinds of damage as it passed through the cassette. I've seen rear derailleurs destroyed when a broken chain was pulled through them so a broken chain is not smooth and snag-free.