Dialog work processes should not be loaded down with long-running dialog steps, as these work processes would then not be available to other users. The remaining dialog work processes would have to handle many more users, thus considerably increasing response times.
This is the reason for the parameter rdisp/max_wprun_time (default setting: 300 seconds), which sets the maximum time a dialog step is allowed to remain in a dialog work process. If this time is exceeded by more than double, the dialog step is terminated and the started transaction terminates with an error. This allows the administrator to ensure that users execute long-running actions only in the background work processes, which are designed for these types of long-running actions.