Templated markup should be prebuilt at build time, usually using a site generator for content sites, or a build tool for web apps.
Faster performance : Serve pre-built markup and assets over a CDN
More secure : No need to worry about server or database vulnerabilities
Less expensive : Hosting of static files are cheap or even free
Scalability : No more worries about traffic
Any project that relies on a tight coupling between client and server.