> Also if there is a compromise, reproducible builds allow you to later track it to the source.
They do not. Git log and build logs allow for that.
Reproductive builds only have value after the source. They protect build servers from being compromised (and then only if some other uncompromised environment is also running verification passes), if the bug is at source reproductive builds are exactly as valuable as writing commit that was used for build in app's code/package metadata.