Also host can't offer that date for another guest (at least it used to be like that). In case of cancelling 1 day prior then they either have a serious issue or another booking so thats not so punishing.

It may also affect internal ranking order by which they show properties to people, but who knows whats implemented internally right now, and what will be in place in 3 months.

In this case it wouldn't really matter. It's fine for weeding out exceptionally-chaotic hosts, but hosts who rug-pull on a once-in-a-lifetime event like the eclipse (whether to re-rent for higher prices or because they forgot to take the listing down and were planning on using the facility themselves) aren't affected.