I think the post explains it about as well as can be: The web browser and operating system environments that now dominate the web no longer support our event model in a reliable or predictable way, so we had to change it to provide a stable API. Of course there was a choice: What we did simplifies the events and kept existing applications wired up, which we hope works for most use cases. The alternative was to remove the events altogether, which would have broken every application. We took the choice to avoid the latter scenario, which I think was a responsible course of action.
I do appreciate that most isn’t all, and that’s frustrating for some apps, but I’m afraid the world changed around us. It wasn’t viable to maintain the old feature in modern environments.