Just to point few of them:
1. Quick deploy of the site (I mean you don't need to deal with servers, installations, and stuff)
2. They can start collecting leads easily
I was just about to ask this. “Why does the world need another web site publisher” is a general version of that question. I think you should answer both.
FYI build some alternate landing pages that are SEO’ed for “square space alternative”, etc.