IE11 is an unsecure browser and doesn't even support numerous HTML5 security features. Any business that still relies on IE11 is asking to be hacked, no more, no less, because it also means that these businesses are still running older versions of Windows.

Now IE11 isn't even an excuse because $current_year ES version can be transpiled to older ES versions.

In the corporate world, yes (sadly), but for personal and free projects I'd say it's acceptable to just ignore IE entirely and at most include some JS snippet to tell its users to get a real browser.