Transparency for video is kind of a niche thing, sure, but when you need it you really need it. A good example would be compositing green-screen footage. (Keying transparency on a specific color is exactly the kind of hack GIF uses, whereas PNG does it properly, with a separate alpha channel.)
Omitting obvious stuff like an alpha channel because you don’t think anyone needs it is exactly the kind of oversight that makes all these “modern” video formats unable to completely replace GIFs. Looping is another example.
And I didn't say transparency isn't needed by "anyone". I said it's very rare for video-ish content.
Apng is better than gif. But its advantages really shine in realms other than video content. They're both pretty bad at video content, even despite looping properly.