(Unfortunately) you’re right with your observations concerning content marketing and curation. Done right and honestly, curation could be for both sides (the curator and the community) a helpful part of a content strategy — as for example some consultants I follow show. (I have to disclose that I’m a PR guy as well as an educator).
I think it’s not the exact same motivation if you curate as a journalist or as an entrepreneur, a consultant or as a teacher — your role may influence your curation and your objectives with it. That was the reason I suggested to get clear about that first and to link this with the needs of your audience. Maybe the term “motivation” is not the best one to express this idea.
But all in all I guess our understanding is very similar :)