Nothing stops me from sticking my dick into a blender either, yet it works fine for most of the things (the blender). Both Java’s notion of final and Kotlin’s nullability work great for 99.999 use cases and you really need to go out of your way to break them.
If you can get a null into a nonnull variable, it can propagate all over the program and people will be defensively checking for it everywhere - final is not like this.
