All packages in Debian are peer reviewed by Debian Developers and the package/build/upload process is transparent.
Reproducible builds are an additional safety net and you can easily check what differs between builds.
You are setting up a strawman [1]. I reacted to the grandparent who stated:
Debian packaging has a nice feature too in that you can check the source used to build it, and any of the packages will be reproducible.
Which is demonstrably false, as the link in my comment shows.
[1] I never said that packages are not peer-reviewed.
There are still quite some packages that are not reproducible:
https://tests.reproducible-builds.org/debian/reproducible.ht...
If you look at the list, including some core packages such as gcc and Perl.