Yes, along with chickenpox I also remember getting measles before the vaccine was in common use (a somewhat more heavy-duty disease and a pretty grim experience while it lasted), plus the so-called Hong Kong Flu that, as its name suggests, presumably originated in similar fashion to Covid-19. The Hong Kong Flu is thought to have killed between one million and four million people at a time when the world’s population was about half what it is today. And so, I got pretty sick then too.
Before that, there was the Asian Flu which was worse, and of course 1918, the very Captain of these Men of Death, to employ an old medical expression.
In other words, really dangerous worldwide viral pandemics have happened every 35 years or so on average. There are no excuses for authorities to be caught on the hop like they have been lately.
Although pandemics like the Hong Kong Flu only happened every few decades, the circulation of other infectious diseases like measles and chickenpox was more or less constant and few children failed to catch several such fevers in a row.
Such childhood infection was often, as you say, encouraged in the belief that many highly infectious diseases were even worse if you caught them for the first time as an adult.
COVID-19 seems to fit that pattern, interestingly enough.
Yet, in a curious irony that recalls the economic theories of Hyman Minsky, whereby stability breeds recklessness, we do find that after several decades of universal vaccination many people don’t appreciate that viruses are physical.
As a famous British comedy sketch has it, you try and tell the young people of today about the bad old days (in this respect), and they won’t believe you!