You could also make the argument that letting the initial variant of the virus run its course may have been wiser than society wide mandates that prolonged it. Given the low infection fatality rate, if everyone under 50 in the US caught it, we would have around 30,000 deaths (or same order of magnitude if my estimate is off) because the IFR for those under 50 is so incredibly low. Then the rest of society would be well protected as well and we would have a high natural immunity against new variants that developed. If enacted worldwide, perhaps the reduced transmission may have avoided the delta surge altogether. Note that the CDC’s projections show that a higher natural immunity would mean reducing cases for delta even with limited masking.

Also the first SARS was far less transmissible. Generally speaking as viruses mutate, they tradeoff R0 and severity. It is unlikely the first SARS would have evolved a variant that was more transmissible and equally fatal.

EDIT: Note that even though increased transmissions can mean more mutations leading to dangerous variants anyways, if the alpha variant were spreading broadly before something like delta was broadly spreading, then the delta variant would contend with a higher natural immunity in the global population, which would make it difficult for delta to take hold in the same way. The CDC’s own presentations show that even a limited increased natural immunity of 35% would mean that delta cases would reduce without new masking mandates or restrictions.