I would like the article more if it didn't paint the twist ending as the only way to write a short story so much as the best place to start learning to write one. Especially as you start approaching 10,000 words, you have ample space to write a complete arc or conflict resolution.
I also don't think a "twist" needs to be so jarring as "it's revealed the superhero doesn't really have powers" or the other examples that were given. When authors think that way, the twists start to get predictable, especially to the editors looking for them. A more subtle surprise works just as well.
I have to agree with you on this. It's certainly one way to write a short story, but by no means the only way. I can think of many short works that have complete character arcs and very engrossing plots without the use of a red herring or plot twist.