This method greatly improved matters but 4 byte resources would have been the cure. Lack of resources is still a problem some time or other for most users, and more often for others. The more applications you use then the more the User area become filled. It includes items such as images, fonts, pens, brushes, regions, palettes, and the like. So the GDI area fills up as you have more graphical objects on the screen.
Applications can use many thousands resources.
If you run too many things, including graphics, you can deplete the User or GDI area. When that happens, you get resource error messages, or unusually behavior, or you crash. However the allocation is actually quite enough in the vast majority of cases. When an program is shut down, or part of it is no longer needed, its resources are released and are now available for use by other programs. In practice only very well coded programs behave in this manner.