No it can't. Not for RISC-V/musl, so I'm sure that must be true for other platforms too.
Once you've compiled it for one platform, you've re-bootstrapped it, at which point you can use the real compiler to cross-compile for another platform.
So.... It can, just not for a particular target platform? Or am I missing your point?
Once you've compiled it for one platform, you've re-bootstrapped it, at which point you can use the real compiler to cross-compile for another platform.