Another anecdotal data point: I managed to make my back pain disappear with a combination of deadlifts, squats with good form and stretching of hip flexors. It also fixed some knee issue (side effect of strengthening the legs I guess.) Having recently moved I haven't taken the time to get a gym subscription. After 2 months of sitting all day I managed to hurt my back while sleeping (yep, it's ridiculous); I couldn't bend to tie my shoelaces for one week...

So yep, I'm convinced lifting heavy stuff is good for your back (IF you use good form, of course.)