I'd say in this case yes. In Go there have been a lot of complaints about Google leading the project in the direction they see fit, with zero input from the community. Often the community has complained and would prefer things done differently, but Google say it should be done their way and that's it.
The way this has been handled just reinforces that Go is not a community project, but a Google project that happens to be open sourced.
> Is it really realistic to make every chat with a colleague into a formal, public RFC?
Maybe, maybe not, but when the community asks for a discussion about something, a response of "too late, we already decided behind closed doors" is not one that builds a culture of the project taking community involvement seriously.
Even if a decision has already been made in private, and will not be changed (which I feel is already somewhat missing the point of a community project), at least showing openness to those discussions, taking feedback, and tracking it in public is important to build the culture that is necessary to make projects succeed like this.
The way this has been handled just reinforces that Go is not a community project, but a Google project that happens to be open sourced.