That's because bad developers focused on WebKit-only experience, forgetting about other browsers.
The same happens when some sites require Chrome to work, blocking all the rest. In 2019 it's unacceptable
The same happens when some sites require Chrome to work, blocking all the rest. In 2019 it's unacceptable
Because it's 100% just a missing feature in Firefox mobile, there's nothing website developers should add to "make it work" on it.