Earlier quoted context omitted.
Do you realise that mutation is not something the species can consciously control? How could the virus have mutated to become milder to suit the social response if the society, as it stands today, is continuing to do what they previously did..?
The lockdown prevents severe mutations from replicating because of lockdowns. Milder mutations don't result in lockdowns hence ...
There's going to be a negative correlation between severity and something like "velocity" of infected persons.