When a feature goes from a “brainstorming” stage(which may include crazy ideas like “give users a ride to the ISS if they sign up 4 friends”) to a “refinement” stage, get everyone involved. By this I don’t mean just the dev managers, I mean everyone, soup to nuts, that will be involved with the feature. Don’t discuss how long it will take. Discuss the merits of the feature, how it could be implemented, etc. These discussions should be vigorous and disruptive (this doesn’t mean be unprofessional). These matter. Alot. If you exclude anyone, exclude managers. This creates an ACTUAL engineering driven culture.
Agile Is The New Waterfall

True. But doesn’t Agile account for this? Parking lot discussions, kaizens, etc. that occur outside of stand-ups can involve any and all stakeholders.