I don't think I actually made that definitive declaration. If I did, I'd be wrong.
I am arguing that your definitive declaration of all the precautions/lockdowns blah, blah, blah made no difference are wrong in terms of there is no way to prove it. As such, you cannot be so sure.
You would need 2 sets of people of equal ages and levels of health, one using precautions and the other not, then exposing them to EXACTLY IDENTICAL conditions (such as exposure to the same people) over an extended period of time and check the results to see if one group or the other did better. Of course, such an experiment would be impossible to conduct. As such, definitive declarations such as yours are nothing more than speculation, your opinion. That is what my argument is.
I do believe that lockdowns, masks, distancing made a difference but I can't prove it and I can't declare that I'm correct. But simple logic (doing things to avoid exposure to the virus would reduce spread) tells us that preventive measures were most likely effective/prudent.