There wouldn't be different brands of clean water, because it's either clean or it isn't. Then we could add a pinch of whatever kind of dirt we're in the mood for. Now, before any of you biochemnerds start emailing me about minerals, electrolytes, and other impurities, think for a minute. The use of the seatbelt. Unless you were raised by wolves, recently discovered by explorers, then took a cab to the airport, you've seen a seatbelt in operation at least once before the flight.
Superfluous instructions are even more common on product packaging.
If you can't handle matches without burning yourself, you're too dumb to smoke. Maybe this is a lesson better learned first-hand. Maybe if you're smart enough to pour acid on your genitals, you'd be better off not reproducing. Felt-tip pens all come with caps, to keep the ink from drying out. If you think about it, you'll realize that the pen can't know that it's got a cap on it.