A bowed or caved-in panel usually starts as one hit - a trailer backing in wrong, a basketball, a kid on a bike. On the steel doors common in houses built around 1976, the skin dents easily because the panels are thinner than what's installed today. You'll see the dent first, then over months the door starts binding in the track on that side as the frame racks slightly out of square.
Cracking is different and shows up more on wood or wood-composite panels from that same era, especially where the finish failed and moisture got into the seams. Kansas winters put real stress on that kind of damage - freeze-thaw cycles open a hairline crack wider every cold snap until the panel splits clean through. If your door is sticking, scraping the weatherstrip, or the opener strains harder than it used to, the panel is probably why, not the opener.