Right, you dont really need them. 
But usually it is a precursor to how the conversation is going. 
I have noticed some people like to zap after a conversation is done. 
Others like to zap while they are conversing. 
Its an interesting mix. 

Satosora

I have and I suspect you get plenty of notifications even without zap notifications.

Undisciplined

The Zen of Hiding Zap Notifications

Traction in conversation, of course. 
That is what is important, you have probably noticed. 
I am open to all opinions. 