How convenient that they all start with an "S"…
Fast by default
Single page application
Progressive application
Lean output code bundle
Built on top of React
A standardised set of plugins
A node application (JavaScript on the front and the backend)
Whatever medley of npm packages you desire
Static files (JS / Markdown / JSON etc)
Plugins to pull in content
APIs like WordPress, Medium, RSS, Twitter etc
Simplified stack
Less to hack
Front-end is contained, decoupled from its APIs
Even stronger without WordPress in the equation
It can be hosted anywhere
We can utilise more modern platforms
Netlify, Surge, Now.sh
Optimised CDN caching
Further reading:
Examples in the wild: