I would tend to disagree with that statement. While the webpack offline plugin is creating the service worker which is putting the requests into the cache storage there is a lot more to achieving a good PWA than just a Service Worker.
You also need to reduce the Time To Interactivity (TTI) to be under 5,000ms. Webpack is doing a lot of the heavy lifting here by performing tree shaking, vendor chunking and route based chunking. All things that contribute to getting this under 5,000ms.
If you would like to know more information as to how to achieve a good PWA, I would urge you to run Lighthouse against the demo which will outline all the things that contribute to a good PWA.
You need to have a manifest.json file which provides all the information for installing your app to your devise. For more information see https://developer.mozilla.org/en-US/docs/Web/Manifest.
You also need to reduce the Time To Interactivity (TTI) to be under 5,000ms. Webpack is doing a lot of the heavy lifting here by performing tree shaking, vendor chunking and route based chunking. All things that contribute to getting this under 5,000ms.
If you would like to know more information as to how to achieve a good PWA, I would urge you to run Lighthouse against the demo which will outline all the things that contribute to a good PWA.