I think a lock down of sorts would've happened eventually, no matter what. Once restrictions are relaxed, a large percentage of people are still going to be very, very cautious. I will not board a plane or sit in a movie theater any time soon.
We moved the economic impact earlier to trade down health impacts. In order for there to not be some similar level of impacts, we either have to imagine a scenario where the disease was many times more benign than it has demonstrably been in some places, or where people ignore news as things get sufficiently dire and continue business as usual rather than dramatically adjusting behavior from normal circumstances. And both those things have to be true in order for the latter not to make a terrifying contribution, which would also make dire economic impacts: dead or damaged people are much harder to get back into the demand side of the economy than housebound or unemployed people.
If you're thinking of worldwide counterfactuals, and know of any society that has a story involving staying broadly open that didn't use effective mass testing and contact tracing early, then specifics would be an interesting contribution.
Additionally, we have saved lives (and animal lives) by shutting down parts of the economy. That should be included as a silver lining to the whole thing.
Isn't that entirely hypothetical though? Find it hard to take such statements seriously when the experience worldwide is so widely varied.
The evidence is clear that lockdowns have caused this economic impact, how can anyone actually make accurate estimates of the alternative?