The vaccine is still the most effective method at quickly and safely improving immunity in a population, and arguing natural immunity as an alternative to the vaccine is effectively a non-argument as there is no rational way to even know where the natural immunity line lies. Furthermore who is to decide who is immune enough to a disease we will know very little about, this would be an impossible judgement to make. If it is left to people to decide if they have enough natural immunity many people will die, and doctors or governments cannot be expected to measure or make such impossible judgements.
The much less dangerous public health policy is exactly what is going on, vaccination campaigns, the vaccine is much less dangerous than SARS-CoV-2 and the best chance we have at saving the most lives. Even the authors of studies demonstrating the benefits of stronger memory B immune cells have stressed that risk of disability and death from an actual COVID-19 infection is much higher than with the vaccine. Natural immunity is commonly held as superior by antivaxxers and as an excuse to avoid vaccination. However the argument falls apart when extrapolating beyond the individual, when thinking about a contagious disease moving through a whole society, and when trying to limit the risks posed to the immune compromised.