I see your point. I have long bemoaned the way that Runaan's works in this game. The fact is that the way statikk works just makes it better, because you can take it for single target burst damage. It works great for that AND has decent waveclear.
Now, in theory, I agree with what people said below... Basically that runaan's is better for teamfighting. Unfortunate truth is... no, in my experience. The reason is that the range for the bolts on Runaan's is pitifully low. I hardly ever get it to actually work well. I sometimes build it anyway, hoping I judged it too soon, and I always wind up disappointed. It's just a bad item, and the rework didn't help. It needs to have that range extended, and Statikk needs to only apply to targets around your main target. With those changes, things would be a lot better.
TL;DR - You are only right in theory. If the items filled their intended purposes, you would be right. But they don't, and Statikk is just better 99% of the time.