The browser can never know what information is needed for a certain use case. So it needs to be permissive in order to not break valid uses. For instance, your list does not include the things a user clicks on the website. But that’s exactly the info I needed to log recently. A user was complaining that dropdowns would close automatically. We quickly reached the assumption that something was sending two click events. In order to prove that, I started logging the users’ clicks. If there were two in the same millisecond, then it’s definitely not a bug but a hardware (or driver or OS or whatever) issue.