In retrospect, herd immunity for COVID doesn't seem like it ever was possible. It's a ridiculously infectious disease, basically everyone has to get infected and even then herd immunity is not guaranteed.
The most likely outcome without lockdowns, even if you isolate the 1-5% most vulnerable, would be catastrophic failure of the healthcare system. Plenty of countries really did try not to use lockdowns, but invariably all countries that didn't have extremely young demographics and tried not using lockdowns were at the brink at least once.
The approach you suggest would have been disastrous without RNA vaccines and from what happened in most countries which lifted restrictions too early, would also have been disastrous with them. The government where I live is one of them and they had to flip-flop on the issue about 7 times as the system got close to the breaking point. Increasing capacity wasn't feasible either because trained personnel was the bottleneck, and even if you could train three times faster, no one would want to do the job anyways.
The problem with health system breakdown is that at some point it's not even COVID that kills people. If that happens, even just a broken bone can be genuinely life threatening. People will start dying of a plethora of things they'd normally be able to easily deal with.
I think you missed the part of the guidance where you lock down the 1-5% of the population that is most vulnerable, but only for 1-3 months.
For Covid, that would have greatly reduced peak health care loads, and had a much more modest economic impact, and fewer secondary effects (RSV wouldn’t have been a issue, for example.)
Locking down 1-5% is not nearly enough, though. Hospitalisation rate just for nauve people above 60, which are a quarter of the population, was above 5%. No healthcare system can handle the hospitalization of over 1% of the population in a few weeks.
The most likely outcome without lockdowns, even if you isolate the 1-5% most vulnerable, would be catastrophic failure of the healthcare system. Plenty of countries really did try not to use lockdowns, but invariably all countries that didn't have extremely young demographics and tried not using lockdowns were at the brink at least once.
The approach you suggest would have been disastrous without RNA vaccines and from what happened in most countries which lifted restrictions too early, would also have been disastrous with them. The government where I live is one of them and they had to flip-flop on the issue about 7 times as the system got close to the breaking point. Increasing capacity wasn't feasible either because trained personnel was the bottleneck, and even if you could train three times faster, no one would want to do the job anyways.
The problem with health system breakdown is that at some point it's not even COVID that kills people. If that happens, even just a broken bone can be genuinely life threatening. People will start dying of a plethora of things they'd normally be able to easily deal with.