When optimizing code it's not unusual to look at the assembly. It's not unusual to look for opportunities for autovectorization or to verify inlining or loop unrolling.

Compilers are, for the most part, deterministic. This means after people have reviewed the output, it's unlikely to change. It also means if they do change, only a few people are required to notice.

None of this applies to LLMs. They are worse than compilers, in regards to the quality and characteristics of their output, in every possible way.

If no one reviewed compiler output then https://godbolt.org/ wouldn't exist.