You don’t have to know about the ADRs to read about it. There was a blog post, and thread covering all the reasons and it was quite public. Even mentions the ADR.
Yaml isn’t going away. That’s why the WTH doesn’t make sense. It’s also why many people including myself are annoyed with the same tired question. This topic comes up every few weeks with or without the month of WTH. Code owners have the choice to keep yaml and the UI when transitioning to the UI. If they choose to remove the yaml, then they can. It’s not complicated. They don’t even have to transition to the UI if they don’t want to.