To give this argument some more meat with an example: some older glibc versions use vsyscalls and not vDSO. And kernels in some modern distributions disable vsyscall emulation. This is a problem because people use CentOS 5 or 6 images to build binaries that are compatible with many historical glibc versions.

If the host system does not enable vsyscall emulation, running binaries on such old distributions will lead to segfaults. (Which can be resolved by booting the host kernel with vsyscall=emulate.)