That's the point made in the line after your quote
> Luckily, human skin is not highly conductive and neither are rubber soled shoes.
Could also note that depending on your circuit breakers, a short circuit will continue delivering higher than its 20A rated capacity for some time until the overcurrent protection goes off.
Thermal breakers won't react as quickly to overcurrent as thermal magnetic breakers, so it depends on what kind of protective equipment is installed.
EDIT: some reference on circuit breakers https://www.se.com/ww/resources/sites/SCHNEIDER_ELECTRIC/con...
> For example: based on the curve on page 3, an iC60 circuit breaker of curve C, 20 A rating, will interrupt a current of 100 A (5 times the rated current In) in: 0.45 seconds at least, 6 seconds at most.
6 seconds is a pretty good chunk of time for a 20A circuit to happily be delivering 100A of current.