Study is based on a mathematical modelling only with a number a assumption made by the authors. As such it is only a proof that mask are effective given the assumptions modelled.
Purely mathematical modeling have produced more accurate predictions for how the spread was going to happen, and so I give mathematical modeling with high esteem.
There were plenty of overestimated predictions, you are cherry-picking the ones that happened to be more right from your memory.
There were a lot of different models. The more purely mathematical models were more accurate. Likely due to them having the least assumptions when so much was still unknown.
Now with hindsight we know more. It was more airborne than a surface bug. Masks worked better than washing things. Contact tracing and testing was an effective strategy.
Since every nation did things a little different we can directly compare all the different types of responses. The more socially responsible populations did better.
