You are absolutely right, lockdowns are just a proxy, the real factor is behaviour. If everybody behaves lockdown-like, lockdown can be avoided.
You don't need lockdowns to stop the healthcare system from being overloaded, if everybody wears masks, socially distances, agrees to track, trace and isolate programmes, there is mass testing, no incentives for people to come to work sick, etc. One year on we have a pretty good estimate how each behaviour/measure influences the reproduction rate of Covid-19.
> Please stop pushing the unproven narrative that lockdowns stop the healthcare system being overloaded.
I don't understand what exactly is unproven. Lockdowns correlate with behaviour. The Chinese healthcare system was completely overwhelmed, even with CCP spin on things. In Bergamo, Italy, the dead were carried away in army trucks. Look at fatality rates for both countries at the time.