Plymouth's housing stock runs mostly 1957 to 2007, with the median build year around 1982, and that era matters here. A lot of these doors are on original track and roller hardware that was installed once, thirty-plus years ago, and never upgraded. Steel track brackets that were fine when the wall framing was new work loose over decades of seasonal expansion and contraction, and a loose bracket is almost always the real cause behind a track that looks bent.
The cold is the other half of it. This area sits in a COLD severe climate band, which means repeated freeze-thaw cycles on the slab and the track mounts every winter. Ice buildup at the bottom of the track, or a door that's iced to the slab and gets forced open anyway, is a common way a roller jumps the rail. Nylon rollers that have gone brittle with age crack in cold weather faster than steel ones, and a cracked roller doesn't track straight.
Doors on original hardware from that 1980s-90s build wave, combined with a winter that stresses the mounting points twice a day, is the pattern we see across this area more than anything exotic.