[Hendrikto]

It allows verifying that the binaries actually match the source, which is extremely valuable.

[charcircuit]

Bit for bit matching is not required for that.

[Hendrikto]

It makes it much simpler and more robust though. Also, it allows for content addressing a la Nix, among other benefits.

[charcircuit]

I reject that those benefits are actually that useful compared to the effort needed to do so.

You can content addressing without reproducible builds. You just have a canonical version, which typically is built by the application developer.