I believe it means abandoned in the sense of railway=abandoned: someone found a boot stuck in the mud somewhere along it, possibly with the help of aerial imagery, and will make sure you know about it if you dare to delete the way. 
Kidding aside, abandoned:highway=path reminds me of the Alamere Falls Trail, which at one point was unquestionably a highway=path but was later abandoned by the maintainer and had its trailhead sign deliberately removed in order to keep people from following it. That said, I don’t think that describes every case where highway=path feels like a stretch.