Election integrity requires as much of the mechanics of elections to be transparent to all observers, including politically-disfavord groups, as possible.

If the voter rolls are state secrets, only available to approved insiders, how can you know they're not filled with regime sockpuppets?

I don't want grocery store circulars on my front porch. They're trash, they're bad for the environment, an eyesore, literal physical spam. But our municipality can't ban them, because First Amendment jurisprudence says so. The circulars are speech and expression at their nadir of protection (commercial speech not of any public or artistic interest), and they're protected.

Good luck getting in the way of political advertising, which is speech and expression at the apogee of its protection.