I think Daffy has it right. One of the reasons why there are so many different initiatives is "Pronoun Trouble". It has to do with fine distinctions between who has "control of the project" and who winds up with "ownership of the result".
In IHE and HL7 both, members are quite accustomed to working on initiatives that are "sponsored" by others. The end result becomes an IHE profile or HL7 standard or implementation guide. Sponsorship can mean many things. In some cases, it just means "promoted", and doesn't really involve any contribution of goods or services towards getting the job done, except perhaps contribution of the "problem to be solved". In other cases, especially where the sponsors have a bit of a clue, it does involve contribution of resources to the project.
ONC S&I Framework projects take a variety of different approaches (one of the challenges of a lack of consistency and governance in S&I activities). On a few occasions, they've started inside or along-side and SDO process (e.g., Consolidated CDA and LRI for example). On other occasions, they've made some progress, and concerned initiative members have move things along inside an SDO in support of the process (e.g., Direct, Query Health and ToC). On other occasions, there was good intent to involve an SDO, but what we are left with is a specification that still has no home (e.g. The Direct Applicability Statement).
I like some of what ONC has contributed as the "impatient convener" in the standards development process, especially in the area of getting interested parties engaged, in running pilots and developing reference implementations, and in contribution of real-world success criteria. But some of it is still troubling, especially with respect to variable governance, communciation, and coordination.
As S&I evolves, I'd like to see more collaboration across SDOs, and better utilization of the limited resources of the standard community (myself included). I'm still thinking about how that could work, just as I have been for quite some time:
Hopefully, someday, we'll figure it out together.