I have "I don't like, only zap" in my profile, which is what it is. Though I occasionally like anyway, on accident, usually when I'm trying to scroll or extend a truncated post on my phone. 
For me, it's just a statement of intent, I don't mind at all if people like my notes, but I'm trying to be more mindful in my likes, so I put some thought behind them all.
I haven't really thought about what I'd do if I wanted to zap and someone doesn't have a wallet linked.