By governance I mean that the blockchain has to have some kind of defined process how to make decisions. If there is no governance process, the result is usually chaos and nothing gets done. You can see this in the case of Bitcoin today: it can't make a decision how to scale. Blocks are full and nothing is done to make situation better because the community can't agree on the next steps.
A well-designed blockchain has a clear process how to make any kind of decision regarding its existence and function. The decisions might be sometimes bad, but at least it can make them.
A good governance process also makes sure that the blockchain can exists for a long time. If the original developers, or "parent group" as you say, are taking all the accountability and responsibility, the system can collapse when any of them leaves. A properly designed decentralized system shouldn't be depended on certain individuals, it should be able to replace anybody easily.