Having come across this discussion recently, my respose is;
In my experience, the essence of BPM is the ability to define an activity from a Business perspective, as it should be, and optionally to allow that to be 'translated' into a specification for automation.
This translation is the key, however. Describing a Business activity is not new. Describing an automated system is not new. Using the same 'language' to do so definitely is.
In the past, Business users would get an analyst to document an activity. This would inevitably (in my experience) be turned into a specification (assuming automation is the goal). This specification would be so technical that no Business stakeholder could understand it. There you had the communication breakdown, and so began the Business IT divide.
In my opinion, and in my experience, BPM and the associated 'language' employed to document processes can bridge that divide and give control of automated system to the business users, for better or for worse.
Having said that, the technology itself is not the enabler here. The 'language' (typically BPMN and similar standards) is the real tool.