Not who you responded to.

It’s like saying you need and app in order to use Instagram

That’s exactly what your Instagram app is: An application to use the Instagram “service”. The only difference is that the app is developed by the same people who develop the Instagram service.

it needs to be an integrated app

In some cases, an app is even just another design of the same web page you visit with your browser. The Netflix app you have on your Windows PC is just the web page wrapped in a certain way so that it looks like a program you find on your computer.

That list up there are what you call “integrated apps”.