Medicine is literally the source of the concept of side effects, the idea that some helpful interventions have simultaneous harmful impacts.

For large-scale infectious disease --- epidemiology and public health --- quarantine and infection/contact tracing are very tried and true containment methods. Yes, these impose costs, particularly on individual liberties. What's key is having a well-governed, principled, high-integrity, trustworthy government which makes clearly-justified decisions as to when to impose such restrictions, and when to lift them. Sadly, this has become more difficult in recent years.

Agreed. The theory is there, and even then sounds like it would work like you said if the government was "well-governed, principled, high-integrity, trustworthy". Theory rarely works according to the plan in practice, so as we see today, even if those qualities had been a priority of the government (which I don't think they really are - I think the government in USA acts more like a rich-man's proxy tricking you a lot) we need the plan that accounts for some rough spots or edge cases.