The Hamlet Defence is clearly built towards teamwork
Ranking systems are not. People came up with the idea of collecting resources and dumping them on someone, but that doesn't mean it was designed with that in mind (Since one person gets all the credit for it, I'd say clearly it wasn't). The ranking system just isn't needed to drive participation. Aren't the relic weapons enough by themselves?

I realize that the advantage afforded to bringing a top 20 contributor is not drastic. It's still an unnecessary e-peen feature, however.