The _tooling_ is not reproducible. Take a not small golang project with some number of dependencies and there should be a single list of the latest versions for the entire project. And exactly what golang commands do you run to generate that list? It's totally broken. This is why so many tools cropped up like go-mod-upgrade and so on.
Everyone downvoting obviously doesn't understand the problem.
You are being downvoted for being wrong and talking about downvoting, which is called out as something not to do in the posting & commenting guidelines
the versions in go.mod are an enforcement of the versions required by your dependencies, and those your module require. asking for it to be reproducible from scratch is like deleting package.json in a node project and asking it to magic all your >= < version constraints out of thin air, it's impossible because you're deleting the source.
Everyone downvoting obviously doesn't understand the problem.