When you have lots of non-randomized dropouts from a randomized trial, that greatly weakens the causal link. The results are effectively non-randomized.

Meanwhile the evidence from actual drinking levels was much stronger (far fewer dropouts) and showed zero effect. Before this trial was done, you may have predicted that there would be positive results for the lab experiment but zero results in ecological conditions. But I think that prediction would be quite unusual. For anyone who expected results in ecological conditions (like me), this was disappointing.