> Firefox addons target gecko, not webkit.
Are they? I've built a few Firefox extension and I cannot recall any part of the API that is Gecko-specific. While parts of the API aren't entirely browser-agnostic, they definitely seem to be engine-agnostic.
It’s not the part you see, its what they see to implement the features you see.
True, but I don't see how that answers the original question of "why does Firefox not support extensions on iOS?". Clearly extensions can run on WebKit. I assume it has much more to do with Apple restrictions rather than with the fact addons are built for Gecko.