This compares GNU's libc with musl (aims at POSIX conformance and being lightweigth), uClibc (size) and dietlibc (size but has no full support?).
It leaves out Google's bionic, used in Android, which is not compatible with GNU's libc... go figure...
So most alternatives aim to be smaller and some also focus on standards compliance (GNU's libc is not fully POSIX-compliant AFAIK).
perfect mathematical harmony = engineered, the aliens did it, obviously