I appreciate now the longer answers, but it still hasnt been explained why the core had to be bumped to 2.3, what was in 2.2 stopping the further development of apollo?
The way it works is as follows:
Most of the times, changes to the OE go step-by-step. The resulting image shows if all is fine, or that there are issues.
Sometimes the steps are big. Nothing we can do about that: the world changes and we have to follow.
In that case it is good practise to create a development-branch; images build from there are tested by teams, while 'normal' builds continue to be build from the master branch. Once teams are happy with the development-branch, public-released images will be build from there as well. And that is the moment teams announce the switch-over.
As a result of taking one or more big steps, backward compatibility (in fact 'forward compatibility) of old settings can't possibly be ensured. So to prevent issues it is always the best to start a fresh flashed and setup image on all concerned boxes.
The same is the case when there is a kernel update for a specific box.
Not much we can do about that. It's part of the update game. if you want images on the bleeding edge of new developments, you should follow, albeit not necessary immediately.
You don't have to update, but you should realize that old branches will not be developed anymore, and in due time feeds for old versions will cease to exist. And because all members of all teams will only use the latest version, support for old versions will be (very) limited.