Communicating mental models to the team because the Architect can't be there every second watching over every team member to guide them personally. By giving actionable mental models, the team members are empowered to make the best decision given the local circumstances.
Software architecture is the story we tell ourselves and our stakeholders.
The art of architecture is predicting the future. In the multi-dimensional realm of software, which dimensions will need to change? Also, what will be difficult to change if it isn't right from the start? In order to create adaptive architectures that will be able to change with our changing needs in the future, we need to gaze into our crystal balls and foresee the reefs and shoals of the software's realm.
Like other endeavors in engineering, this is about identifying risks (and opportunities), and managing those risks.
Simon Brown https://www.youtube.com/watch?v=9Az0q2XHtH8 https://riskstorming.com/ Booch quote about architecture being the things that are costly to change. AaaS - Architecture as a Service (don't do this)