Yes - the problem is when the default group gets the email because there is no one assigned to the responsibility type.
90% of the time, your response above makes sense. But we have "change notification" type workflows where it isn't necessary to include the default group. This is why we'd like the ability to decide if a step can be skipped, or if someone needs to get the notification. Backup responsibilities can cause confusion in this use case because users get notified about the same asset/change multiple times (ex: I got notified as the Owner, and again as the backup role for Steward).
Your message has me thinking though - is there a way to bulk assign users as followers (instead of self-following)? If we could mass assign followers, we could change our notification workflows to only notify followers. We don't want to ask users to individually select hundreds of items to follow, which is why we use the workaround I explained above.
I hope all of that made sense! Let me know if you'd like to have a 10 min call instead.
Thanks!