I don’t think you realize how anti-scientific an attitude you’re expressing here. If there is “evidence for the social contagion model”, this kind of analysis

I don’t think you realize how anti-scientific an attitude you’re expressing here. If there is “evidence for the social contagion model”, this kind of analysis would be a natural step in developing hypotheses about where and how to look for it. And if there’s none to be found, those hypotheses will eventually fail to hold. That’s the method. If you choose not to collect data or test hypotheses because you think a question is “most definitely” settled, then you’re not practicing science. You may be saving wasted effort or managing some kind of socio-political dynamic, which may be more important to you, but some people appreciate science specifically for its ability to upend “most definite” knowledge now and then.