This calculation would make sense if they could keep cases restricted to limited regions and then stamp them out, which seemed to work with earlier variants according to official reports. It hasn't been working with Omicron: the cases are appearing everywhere in the country, they're struggling to stamp them out even with strict lockdowns, and by the time they start to lock down the virus has already spread to people outside the lockdown zone, probably several steps away from anyone who's been in it.