Rendering HTML templates / JSON
Asset compilation / Cache busting
Caching
Sending Email
Previewing/Testing Email
Background Job queuing(with failure/retry/backoff)
Reliable and easy integration/feature testing
Connecting to database and modeling data
Authentication / Account signup / Confirmation / Forgot Password
Security
Payment handling
PDF / Invoice rendering
Deployment
Making pretty good money over here and how many ROFL scale GO routines I can run never really came up.
¯\_(ツ)_/¯