why new GnuPG packages when it is dynamically linked ?

Hello, when doing ldd /usr/bin/gpg I get libz.so.1 => /lib/libz.so.1 (0x40026000) so GnuPG (on SuSE 7.3 at least) seems to be linked dynamically against libz, so it should be enough to update libz, but why offers SuSE a new gpg package although it's linked dynamically against libz ? Thanx Malte