@btipling
"Burn this article in a fire" :)
Looking back through my article I agree that stating delete should outright never be used didn't make sense. It's of course used in numerous JavaScript libraries and has a purpose in the language. I've updated the text to reflect my suggestion that it should be instead, avoided where possible. This advice stands as it's more difficult for V8 to optimize objects you're changing the structure of.
For others commenting on this thread, I've also taken account of some of your suggestions and tried to update the article to be as accurate as possible. Thanks for the input!