I use a clang/libc++ toolchain to target Linux, macOS and Windows - works like a charm. It's also the toolchain used by Android and iOS, and I could also do some WASM with it. So portability here is definitely not an issue to me
c'mon, clang is able to target x86&64, ARM, AArch64, MIPS, AVR, RISC-V, WASM among others - those combined are 99.9% of the market (and 100% of the market for desktop apps).
sure, there's nothing wrong with self-inflicted pain. Rust shows that a compiler monoculture works much better in practice.