[eru]

The problem you pointed out is real, but determinism in compilers is still useful!

Suppose you had one of those widely unstable compilers: concretely if you change formatting slightly, you get a totally different binary. It still does the same thing as per the language spec, but it goes about it in a completely different way.

This weak determinism is still useful, because you can still get reproducible builds. Eg volunteers can still audit eg debian binary packages by just re-running the compiler with the exact same input to check that the output matches. So they can verify that no supply chain attack has fiddled with the binaries: at least the binaries belong to the sources the are claimed to.

[wat10000]

It’s useful but far less important. This is easily seen by the fact that we went decades building lots of software without reproducible builds.

[eru]

If you go further back in history, we went even longer without building any software!

No clue whether that's a good argument.