User blog comment:Mira Laime/Get the latest on your favorite entertainment fandoms with our new app/@comment-31294034-20171004022322/@comment-126761-20171004193857

Regarding ES6 - we still support IE11, so user scripts do still need to function on that browser as well. While we do recognise ES6 support could be helpful for writing scripts, keeping things working on all supported browsers is a greater concern at this time.

However, as people move to more modern browsers (and IE11 support is eventually dropped), it's probably this situation will change.