You seemed to have missed the author's point.
Superhero stories were supposed to represent an escape from the old, adult-focused form of entertainment. Where they ended up was of course just another form of it.
The money quote is: "Wallowing in death isn’t a sophisticated leap beyond the superhero concept; it’s the failure to imagine what it means not to die."
You can liken this to the sitcom. Storytellers had to envision a platform upon which an endless number of stories could be told in a particular format, without getting boring. The setting, including the characters, have to remain static. Breaking the sitcom mold doesn't make for an evolved sitcom, it makes for a devolved one. One that brought back all the problems that the sitcom format resolved.
Superhero comic books had to appeal to seven year-olds, while still retaining enough in there to keep the teens and then adults they grew up into entertained. You need a story that can live forever, and still remain interesting. The bad guys have to get handled with a minimum of fuss, and understated magic, such as Batman never killing anyone, is an appropriate storytelling device. The morality play, good beating evil, and all the whimsy and silliness that conjuring it entailed, is just part of the superhero format.
Without all that, they're not superheroes, they're just story protagonists with special powers that are sometimes heroic. That's the argument the author's making.