Well, I can, because all the evidence is that those actions had absolutely no effect.
You don’t need a binary all-or-nothing scenario to conduct an observational study on the effect of mitigation efforts. You just need different locations doing different things. If you ever bothered to use Google, you’d find that several researchers have attempted to determine if there is any relationship between the ‘severity’ of mitigation measures and mortality/morbidity. The correlation is basically zero; most studies found a slight detrimental effect associated with lockdowns, although IIRC it was not statistically significant.
Having said that, the control groups that you think do not exist are in fact out there.
Most African countries did precisely nothing to “control” COVID, and they (supposedly) have the lowest impact of the disease. No doubt you’ll suggest they’re just lying, and I suppose they might be, but the fact that they can get away with lying without having to hide mountains of corpses suggests that COVID didn’t hit them that hard. The more plausible explanation is that their younger populations genuinely weren’t affected.
There’s Sweden, of course. You can’t exactly say they did nothing, but they certainly didn’t attempt to force the whole population to do X, Y and Z “for their protection”.
I spent the whole of 2020 in a location where the response to COVID was … erratic, at best. None of the interventions had any scientific validity, and served only to plunge thousands of people into depression and poverty. Those measures were soon (mostly) abandoned, except for a desultory show of checking papers and similar nonsense. I never heard of anybody actually getting COVID until the vax programme kicked off in mid-2021. At that point everyone seemed to be getting it, although deaths remained low.
The Amish went out of their way to get COVID over and done with. They’re hard to study because of their reclusiveness, but as far as anyone knows COVID blasted through their communities pretty fast, and their death and morbidity rate was no higher than, and perhaps somewhat less than, the remainder of the US. Amish are mostly anti-vaxers. Pennsylvania, Ohio, Indiana and Wisconsin together have recorded exactly the same rate of COVID death (2.6/1000) as the US as a whole - the Amish population is small, of course, but presumably if they were dropping like flies you’d see that register in the State death toll.