What did people think would happen?
We thought that if we didn't do that we'd run a very real risk of the entire healthcare system collapsing. We were trying to "flatten the curve" so that hospitals could deal with an ongoing roar instead of being hit with a massive explosion.
Not were, are.
The entire lockdown/restriction/mask mandate set of policies has been based on managing hospital capacity. State and local governments are still using hospital capacity to decide when to lift or reimpose restrictions.
The wave of explainers we got last year about flattening the curve were wrong about how long it would take, but the fundamental strategy and the reasoning behind it never actually changed.
We'll never know for sure, but I doubt that's the correct comparison. Even without government-mandated shutdowns, many areas--especially major urban cores--would still have experienced massive shocks as people voluntarily shifted to working from home, stopped going out to eat, etc. In other words, much of what the government did through law would likely have happened anyway out of fear and individuals exercising their common sense.
Sure, it wouldn't have been exactly the same, but I think the counterfactual is much less rosy than you assume. And then there are the benefits of the shutdown which helped to direct the drop in activity towards less essential parts of the economy and increased predictability, to say nothing of the benefits of reduced viral transmission.
Lessened demand in large sections of the economy can itself create shortages in the parts that take on the load or at least stress on the supply chain to redirect to those places now in extreme demand. Take restaurants for example, people didn't stop eating but vast swaths of food supply chains had to change pretty much overnight.
Then there is also the problem of the demand of certain things being highly uncertain, like cars towards the beginning.
Then there is the extreme induced demand on certain things like webcams, laptops, or other home electronics as everyone stays home. I'm sure that also isn't an easy overnight change to make and then swing back from since it was completely unplanned. I know the area I work immediately ran out of widgets based on orders of 10s of thousands instantly coming in and it has been backed up since that time to this day.
Finally during the initial portion of the pandemic lots of factories, both in the US and China, were getting shut down. China seemingly longer. When restaurants and whatnot started to open back up was about the time you saw those shutdowns stop happening too. So on top of the above concerns for the supply chain lots of non bars and movie theatres were also affected by shutdowns, just perhaps not as long.
May be more I'm missing but I don't think GP is an empty comment by any means.
e.g., The induced demand from work from home you mention I wouldn't count as part of any 'shutdown' at all. It has been largely driven organically by the decisions of individual firms and workers. My office was ordered to work from home by company HQ, not by any government authority, and at this point staying WFH is an individual voluntary choice. Does this count as part of the 'shutdown'? Certainly my sector of the economy (software development) was not shutdown, quite to the contrary.
It's certainly true that collectively, society pushed down in some places and things popped up in others, sometimes in obvious ways (going remote creates demand for laptops and cameras and office chairs) and sometimes in surprising ones (spiking rental car prices, yet internet providers were totally unfazed). I don't think "if only we hadn't been so foolish as to shutdown a large part of the global economy" is a useful or helpful way to think about these phenomena, though.
How do you envision the time between march 2020 and the point where herd immunity through vaccines / infection would have been sufficient would have gone without a lockdown?
I'll take a lack of a few non-essential luxury goods for a year or two over a world where everywhere looked like that, any day of the week.
https://apnews.com/article/new-york-andrew-cuomo-us-news-cor...
But New York also has a subway system that (approximately) everyone uses to get around. That turned out to be a perfect spreading ground for a respiratory virus. If I understand correctly, that's a big part of why New York got hit so hard. You can't just pin it on Cuomo's criminal irresponsibility.
The places which were closed were not producing things used in the supply chain.