When you compile GCC you need to provide a full glibc installation as your target. It is also a dependency of libstdc++.

C++ global/static variable initialization depends on the specific version of glibc (they don't usually break compat, but they can and they did in the past) which also provides ld-linux.so that loads those global variable placeholders in the correct manner such that glibc and libstdc++ can initialize them correctly.

This is just one example. Thread local variables and behavior of things like pthreads with signal, fork etc all depend on glibc.

I can't comment on the C++, I can imagine there plenty of issues, but for C I don't see this. You need some libc if you compile with gcc, but this generally does not introduce a hard version dependency on the specific version (there may be a minimum requirement if you compile against a new version that a symbol with a different ABI).