Almost everything uses libc, so that's an easy one. But after that, libraries tend to be domain specific.
For example, all C++ programs will probably be linked against libstdc++. Programs compiled with gcc have a good chance of being linked against libgcc_s.
All desktop applications are probably going to be linked against libgtk or libqt, libx11, and various other X libraries. In short, there's a significant, obvious benefit.
As I mentioned somewhere else though, if a library is only used by a single application and that library and application are built together, then yes, you might as well statically-link it unless there's some other requirement.
For example, all C++ programs will probably be linked against libstdc++. Programs compiled with gcc have a good chance of being linked against libgcc_s.
All desktop applications are probably going to be linked against libgtk or libqt, libx11, and various other X libraries. In short, there's a significant, obvious benefit.
As I mentioned somewhere else though, if a library is only used by a single application and that library and application are built together, then yes, you might as well statically-link it unless there's some other requirement.