Debian and Linux Kernel do want it.
Debian patches the official Synfig code to ensure it due its policies for software distribution.
Reasoning is stated here: https://reproducible-builds.org/.
So, should we follow this idea?
I think we have an old version (v1.2.2) packaged for GNU Guix which is definitely THE most reproducible package manager out there…
To be able to reproduce 1-to-1 binary output means to have a very strict environment definition, invariant, without updates (or at least fixed updates version numbers).
Already there is an “official” build environment based on a Docker image (still same problem with update).
Which environment to define? The one according our needs or the one depending on their distro?
After, if it just to avoid to include some modifications like for the time stamp, why not 
Done: