Why aren't timelines calculated from dependencies and durations for tasks?

We are establishing a template project, with tasks that have dependencies and durations established. The “Project Start” milestone activity is the root of dependencies.

However the Timeline fields are NOT calculated from dependency + duration for predecessor tasks.

Do we really need to MANUALLY calculate the timeline for each task?1

The whole purpose of project management software is to eliminate error-prone manual calculations.

What steps should I be using to eliminate the need for MANUALLY entering timeline values after creating tasks with duration and with appropriate dependencies specified?