Earlier quoted context omitted.
What is the difference between a Gantt chart and a dependency graph?
Gantt charts typically have resource assignments and time estimates. Dependency graphs just say Bravo requires Alpha to be completed first (for example).
Dependency graphs can also be annotated with the resources required for each node or edge. Resources are estimated by summation, time is estimated by finding the critical path.
Gantt charts are a partial linearization of a dependency graph. People tend to fixate over the dates shown, allow schedule pressure to "correct" previous estimates, etc.
According to some early users of Gantt charts, they are a great tool for summarizing a plan, a terrible tool for developing and maintaining one.