Not re-hydrating can kill as much as half of the yeast. Most of the time that only delays the start of fermentation by a few extra hours.
It shouldn't make any difference in the final gravity and sweetness, just take a little longer.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk