Most companies have an internal process for the creation and execution of outbound email campaigns (and hence Customer Journeys in D365 Marketing). Yet there is currently no way to enable Business Process Flows for Marketing Emails or Customer Journeys. It does exist for Event Management which is helpful for events. Ideally, there would be a default, best practice BPF for Marketing Emails and Customer Journeys with the ability to customize it like all BPFs in Dynamics.