I look at it this way: the manufacturer says re-hydrate. ALL dry yeast manufacturers say re-hydrate and they give very specific reasons for doing so. Adding it per the kit's instructions will kill 50-60% of the yeast and weaken the rest.
Even so, the batch will ferment.
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