Again that doesn't matter, as there wasn't any better alternative for animated pictures on the web. It's kind of embarrassing that we're still using an image format for animated images that's limited to a colour palette dictated by 90's hardware. If some aliens came to visit and saw how animated gifs are still the dominant animated image format on the web, they'd be laughing at humanity so hard.
Without digging up that old horse, I saw little value in "show the first frame" of APNG - if you want an animation, the first frame is practically useless. Even worse, it may give the user the impression it's supposed to be a static image, while a "missing support" box lets the user know it's supposed to be something else.