Why do no browsers apart from Firefox support animated PNGs? [closed]

Question

When I look into the list (http://caniuse.com/apng) of supported browser on animated PNG, I found that basically only Firefox support it. All the other major browsers don't support. Even the Opera which they once support it and they drop it on newer release.

I always thinking animated PNG is nice. But why is most browsers don't support it? What is the reason they not support?

Answer 1

Google developers discussed it here: https://groups.google.com/a/chromium.org/forum/#!msg/chromium-dev/2xvXNJMsgxc/2CJ9jl-jItcJ