We could categorize controller into two groups, when they use finalizers and when they don't. The framework not handles these cases intelligently. Like we add finalizers, and trigger the cleanup funtion when needed. Howeever there are corner cases whis is hard to cover with this approach:

1. What if user maintains an expicit in memory caches, that wan't to cleanup when on delete event. But don't want to use finalizers
2. What if some of the custom resources requires finalizers but others don't.

So for sake of completeness would like to introduce "all event mode", where the reconcile function will be triggered on every event. .In this mode Cleaner interface is not allowed. And user is free to manage with finalizers, react on delete event inside the reconcile method.