No CI/CD — You have to set it up yourself. Once you use Netlify/Zeit, you will never use S3 for static hosting again.
That's great if all my company makes is static websites, but if we have a bunch of other CI/CD for other projects, I'm not going to introduce a new tool for people to use to make an already simple pipeline simpler.
Setting up CI/CD via CodePipeline for a static website is trivial. Beyond that, Amplify Console offers an extremely easy experience deploying static websites, with built in blue/green deployments.