As many have mentioned the real reason is to suppress votes by making the experience miserable.
The cover story for the rules is to prevent campaigns or other groups from "buying votes" by giving people in line food/water in exchange for a promise to vote for their candidate.
I can't be the only person who instinctively trusts a product/brand less the more I see ads for it.
The biggest example is alcohol brands. It's almost guaranteed that the more advertising a brand does, the more middle-low quality is. (There will always be the ultra-cheap option with no marketing of course.)
It's mind boggling to me that in this modern interconnected era that this isn't obvious to everybody.