Don't agree at all - your own data disproves your argument.
"It was already very clear in February that this disease rarely killed anyone under 60,"
CFR 0.5% for 40-49
You do realize that 40 is not that old? And that 0.5% CFR is really quite high?
Are you maybe one of those '22 and feeling indestructible' people? How could someone possibly talk about 0.4 CFR and greater CFR for an age-diverse population and not realize how extremely dangerous that is?
And it's 'quite serious' for probably 8-14% of those - and that they may get life-long consequences?
And the CFR jumps quite high when there is a lack of medical facilities?
And the R0/transmissibility is really quite high, not like some 'rare disorder' - it's something that without suppression almost all of us will contract. The 'young and partied' are now becoming walking Death Adders, it's a 'systematic issue' and not very helpful to point out that 'some are less likely to die' just as they are the 'root cause of spread'.
Even if was just to 'protect the elderly' a the shut down was easily warranted.
There are 200 000 deaths from COVID more than US Combat Deaths in Iraq, Vietnam, Korean wars combined - in just a few months.
This is the most devastating and deadly thing to happen to America in at least a century, the lock-down was reasonable, there were probably even other measures we should have been taking.
Social distancing on an interpersonal social level is 'economically inexpensive' for god sakes, we're more resilient than to have to be able to 'party' every week or few.
We have to be smart about this but all things considered we have no choice.
What we 'could have done differently' was probably a) react sooner b) move more aggressively in elderly care c) wore masks and d) had a plan for this ready beforehand instead of making it up as we go along.
Edit: Please do the calculation given: 1) your stated CFR rates 2) the 'herd immunity threshold' of 60-80% of population infected 3) an aggressive R0 meaning that this would happen quite quickly 4) adjustment to CFR given overflowing hospitals and lack of available staff - and the numbers are excessively bad, at very least millions dead, which is a monumental risk.