We have a kind of disconnect between the advice people are being given, and what is actually happening. Self isolating after testing positive isn't necessarily bad, unless it begins to infect the economy.
The problem is, if you test positive today that means that you have developed antibodies... a process that takes time. And that means you were infectious for between 3 and 15 days before depending on the variant and the health of your immune system. Also if it's Omicron 1 or 2, I wouldn't worry. You can take all the measures you want (even in China) and it's still going to infect every human on the planet, probably even multiple times - and each time will boost our total herd immunity.
If you are at least double vaccinated, even without a third booster - this is good news, because the chances are you will have anything between a sneezing fit, and what feels like a bad cold for 3 or so days. The people going to hospital are largely people with comorbidities, or who have never been infected.