This may work in Europe or other northern countries but some countries are hot (35 degrees Celsius / 95 Fahrenheit) all the time. A summer off to hobby/vacation would mean never working.
Certainly, a/c also allowed humanity to live healthier in more places than ever before. Like I said, it's mostly an interesting thought experiment, especially because you can often look up what life was like in your area before a/c. In many cases none of us want to return to 100% of that lifestyle, but sometimes there are interesting answers there.
Part of the reason I started joking that a/c was a mistake was a friend noted how much of the drama of Southern US literature surrounds hot weather and commenting on such. There was an idea that all of the "best plays" such as Gone With the Wind, some of August Wilson's plays, and seemingly the majority of Tennessee Williams' plays, devote _a lot_ of the dialog to just how hot it is. That often leads to character's own tensions and dramas boiling out. It shows up in a lot of books at the time too, like Fitzgerald's works (The Great Gatsby). That lead to me joking that maybe a/c has lead to a great suppression of our emotions and a lack of good drama in our lives. It's obviously more a correlation in those works than a causation, but in its own way an amusing thought experiment in the different tempos of life in such places before and after a/c.
