So you do not need it as you do not want to use it too soon. That is cool. Others may need docker image release aligned with regular release, and I think that there is nothing wrong with that. Especially for the people that are trying to contribute to Go by testing beta and rc releases.
We already have a reply to that in your case with the availability of the docker image.
In general, people do not rush into upgrading to a new release of any software because it's risky.
> There are already a lot of work and testing done on projects that depend on 1.12 features
The only reason I can think of is that you have a requirement to support TLS 1.3.
And there is no 'delay', as, surely, you plan based on the availability of everything you need (or build your own container image).