its not over-looked; but there have not been any recent binary releases - the current versions are in source code form only
http://git.savannah.gnu.org/cgit/gnuzilla.git there are community packages though - fedora, guix, and parabola have icecat binaries packaged, and there is a debian package on the OBS, and a PKBUILD on the AUR - those would be the easiest way to use the current versions https://software.opensuse.org//download.html?project=home%3Alosuler%3Aicecat&package=icecat
