Look into the JAMstack. This is precisely what they are doing. In essence, it's having a static front-end markup, leveraging API's for all your heavy lifting needs, and utilizing JS when needed to make your sites interactive or reactive.

https://jamstack.org/

Here's a great talk on the principles of the JAMstack by one of the leaders in the field, Matt Biilmann, CEO of Netlify. He covers the essentials in about 5 minutes, but the rest of the 19 minute talk is worth listening to https://www.youtube.com/watch?v=c5UEHm8Kets