I don't disagree with your linked comment. But my personal experience, not to mention the high level of hospitalisation and mortality at the time which resulted in the first UK lockdown, disagrees with your "Vanilla strains were milder than beta/delta." statement, if "Vanilla" was the variant circulating in the UK in March 2020.
My understanding is that newer strains aren't much different in terms of severity, but the hospitalization and mortality rates will change by some percentage because our treatment protocols improved. When covid first hit, people had no idea what to do with the infected. Doctors around the world were sharing information and research was underway but they all had to learn as they went along. Eventually things were bound to improve, even if the virus hadn't evolved at all.
