pip is an easily resizable overlay, sure you can set window always to front but then you can accidentally click it , like easily drag it around the screen away from whatever I need to see and use to an area thats currently unused, quick resize if I need to see it bigger, its just convenient. Using windows is a hassle compared to it, just open youtube with any browser, click the top tiny square button in the video for pip and youll see what im talking about.

Typically I use it to watch stremio, it isnt as resizable by itself and its annoying to have my keyboard controls switch to a different app, this avoids that. Also if installing something you can have a tiny little window anywhere on your screen over your stuff showing progress.

https://extensions.gnome.org/extension/6816/wtmb-window-thumbnails/

Why would it need to be easier? It works great has high performance? It just happens to be a gnome extension rather than a general linux app, is that what you mean, like use it outside gnome?