You're confusing strong evidence for causality with establishment and absolute proof of causality. This is even discussed in the sources you've cited (second link). For example here is a quote from one of your sources about the necessity understanding the underlying mechanism before causality can be established:
> A causal mechanism is the process that creates the connection between the variation in an independent variable and the variation in the dependent variable that it is hypothesized to cause (Cook & Campbell, 1979:35; Marini & Singer, 1988). Many social scientists (and scientists in other fields) argue that no causal explanation is adequate until a mechanism is identified.
> A causal mechanism is the process that creates the connection between the variation in an independent variable and the variation in the dependent variable that it is hypothesized to cause (Cook & Campbell, 1979:35; Marini & Singer, 1988). Many social scientists (and scientists in other fields) argue that no causal explanation is adequate until a mechanism is identified.