You would care if you were on one of the dozen or so CPU architectures that would suddenly become unsupported.
[1]: like when PyPI cryptography first switched to Rust and broke ansible/openwrt/etc.
We're just not there yet.
Still, looking at https://llvm.org/docs/CompilerWriterInfo.html, it is hard to find an architecture that Clang won't support that is relevant to many people. And if someone does find one, well, Clang is open source and open to adding more architectures.