Late-1990s production tract doors came with steel track bent to a standard radius and bolted to jambs that were framed to code at the time, not to the door hardware that eventually got installed. Over twenty-plus years, lag bolts holding the track brackets work loose from repeated door cycles, and the bracket shifts a fraction of an inch at a time until one day a roller walks off the rail entirely, usually on the side that takes more daily use.
The other common cause is a door forced past an obstruction - a bike, a trash can, ice chest, anything left under the bottom panel - with the opener still pushing. The opener doesn't know the door hit something; it keeps applying force until the track bows outward. On a steel door with roll-formed track, that bow doesn't spring back. Climate here runs moderate heat rather than extreme swings, so we're not chasing the kind of thermal expansion/contraction cracking you'd get in a harsher band - the fault on these doors is almost always mechanical, not weather-driven.