@dandylover1 @FediTips it gets rid of the browser 'chroming' (the tabs, the headers, all the extension toolbar stuff) so you JUST have your app, acting like an app. It can be separately sized (without impacting what a new browser window will open as), separately iconified.
Take a music player - it isn't a web page. It is an app. It just happens to use web-tech. By installing it as a PWA, I can control where it goes, give it its own icon, and more, and THINK of it as an app, not a web page.
Here are two views of my own music player (a client for #Subsonic). One is a self-contained app interface. The other is...an annoying tab in my browser. Buried when I am in another tab, distracted by all the 'stuff' around it. Just...meh. If you want to keep to the tab, fine. But I find having an app be separate is more aesthetically pleasing.