Why does Naut's ult fizzle if he dies before it lands?

As a long time naut fan and player it always seemed like a "bug" to me.

You ult, it's NOT A channel, yet it "stops" if you die before it lands.

Meanwhile people like Brand, Fizz, etc have similar ult mechanics yet theirs do not "fizzle" if they die after casting them (but before they land).

So why does nauts? It doesn't do nearly as much dmg as either of the aboves and I see no reason why it should since it isn't a channel.