79°F can become intolerable as the humidity rises... as it will in an
un-A/C'd house. You should see the buckets of water pouring out the
heat-exchanger drains, even here in Arizona.
Oh sure, put a fan in the window for comfort ventilation, but that's a
far different thing than running the A/C.
When you don't have central A/C installed and on at the touch of a
button, you learn about less drastic measures that can make a huge
difference. And if you finally break down and get a window A/C, you do
sensible things like hole up in room where it is when it's hot enough
to need it.
I finally bought a window A/C for my bedroom this last summer. And
even then, I probably lifted the window sash and inserted a little two
fan unit on top of it far more often than I actually used the A/C.