What are the disadvantages of self-tapping screws?

One disadvantage of self-tapping screws is that they are not as strong as other types of screws, such as machine screws. This is because the threads on self-tapping screws are created by the screw as it is being installed, rather than being pre-formed on the screw. As a result, the threads on a self-tapping screw may not be as deep or as consistent as those on a machine screw, which can make the screw less strong, and less able to hold together heavy or dense materials.