Learnability and usability are related but independent concepts. This feature is difficult to find out about unless told, relatively easy to remember once you first learn about it, and very intuitive once you try it out. Dragging from the corner is slightly easier to stumble upon or infer, but most people will learn about it because they were told about it. The alt drag version (both for resizing and moving windows around without having to go to the title bar) is in addition, becomes second nature quickly and is significantly nicer once you learn it.
Learnability and usability are related but independent concepts. This feature is difficult to find out about unless told, relatively easy to remember once you first learn about it, and very intuitive once you try it out. Dragging from the corner is slightly easier to stumble upon or infer, but most people will learn about it because they were told about it. The alt drag version (both for resizing and moving windows around without having to go to the title bar) is in addition, becomes second nature quickly and is significantly nicer once you learn it.