We're building for early-stage technical teams and independent developers that want to reduce the iteration time on prototype -> production apps.
One note: we have some lightweight persistent data stores built-in for convenience, like a key/value store. However, you're always able to build on top of your own database / API and most of our early users do.
Why would a person use this over salesforce, Wordpress, or the dozen other CMS systems out there? I watched the 5 minute demo, it is doing nothing complex. How many one off sites we all seen that are written by a tool that ended up not able to handle the complexity. Tools like this need a huge "never" been done before hook, and this one does not readily have it.