Another end zone rationale question

[mbyron]

That's actually 2-4-1 (with hyphens to denote a rule, rather than dots to denote a case).

And yes, that answers voice's question: the runner has possession as the ball breaks the plane, but the receiver must demonstrate possession after coming down with the ball in order to make a catch.

To put it differently: on the running play, the ball is dead once the ball breaks the plane of the EZ, hence no fumble. On the pass play, the ball is not dead until it is caught in the EZ, which doesn't happen until after the player returns to the ground with possession.