Among the default tabs, I can understand the purpose and speciality of all tabs except the Modelling tab. What is it for? It looks the same as the Layout tab when I pressed the “tab” key to edit an object. People would rather press the “tab” key in the Layout tab to edit an object, than switching to the Modelling tab, wouldn’t they?
It lacks the timeline which you usually dont want for modelling and by that you gain a couple of pixles.
Personally I dont use it either but some people want every possible pixel they can get.
Each of those set-ups are for different phases in Blender work. The Modelling set-up allows for maximum screen area while modelling. I don’t use most of those tabs and just delete them, but I’ve gotten used to switching between the ones I do because I can set them up the way I want them for how I work. It’s easier than switching window modes back and forth between Timeline and Graph Editor, for example.