This might be technically challenging to accomplish. For example, how do you know a community is actually gone? There are certainly some ways to know positively if we are told, but we might not know about all cases. Community hosting is federated across many servers not all of which are connected at all times. I’ve seen entire instances vanish without explanation.

Visibility is another problem. Sometimes, there are multiple copies of the community hosted in different places because those instances might not be directly federated.

I’m not saying it can’t be done, but I’m not sure how often we know for sure when a community is lost, in the same way we are unsure if a friend has died if we lose contact unless there’s some other means to check on them.

Be the change you want to see..

There is nothing stopping you from gathering that data and publishing it every week.

I will point out that the absence of any messages from a community is not an indication of the end of that community, nor am I aware of any process to "scrub" a community, unless you're referring to the act of an instance administrator deleting a community on their own instance.