You mistyped PoW there.
LN promotes spam resistance only for the sender and receiver, cause only they can tell if a payment (zap) is real or not. Any 3rd party cannot tell the difference between a payment and a self-payment.
Outside of direct connections, distingushing spam from non-spam becomes exponentially harder, the further you go down the social graph.
Problem is, there will always be good content voiced through anons. Any platform with a spam filter that ignores this is self-limiting.
A good way for anons to cut through the bot noise is with PoW.