Virtual memory is what lets us write programs pretending that we own the entire address space, and it is very useful.
Swapping pages to disk, though, has been useful for a very long time. Yes, once your high-performance application starts swapping all the time, your performance is going to suffer by several orders of magnitude. But occasionally swapping pages in and out of disk is part of what makes modern operating systems useful. You left a large PowerPoint presentation open for several days, but never got around to working on it? Not a problem, since if the OS needs that memory, it will just swap out the pages. Without that ability, the OS would need to go around killing processes. (Which it will do if it has to, but it's a rare event because it can swap out pages.)
Virtual memory is what lets us write programs pretending that we own the entire address space, and it is very useful.
Swapping pages to disk, though, has been useful for a very long time. Yes, once your high-performance application starts swapping all the time, your performance is going to suffer by several orders of magnitude. But occasionally swapping pages in and out of disk is part of what makes modern operating systems useful. You left a large PowerPoint presentation open for several days, but never got around to working on it? Not a problem, since if the OS needs that memory, it will just swap out the pages. Without that ability, the OS would need to go around killing processes. (Which it will do if it has to, but it's a rare event because it can swap out pages.)