It also probably caused a lot of people to not be able to say goodbye to their loved ones, or miss their holiday, or whatnot. People don't travel exclusively for frivolous reasons.

I am not suggesting that airlines should see their operations as non-critical (and let a third party make arbitrary untested updates to their critical systems).

But maybe some organizations using air travel can learn from this. I am still hoping that the pandemic will have had some lasting positive effects (on top of all the pain it has caused).