There is a kill threshold even for farming. Setting aside anti-farming, whether it's pre-flower farming or zero farming, there is always a kill threshold. When farming the same project, some people get big results, while others get small results or no results at all—that's being "killed." The same simple interactions can be scripted; if you only do simple actions with high probability, you'll end up with no gains or small gains. Project teams wouldn't be so foolish as to give airdrops just for participation.