I would hope they didn't get stuck there. That would be pretty terrible. To have gotten stuck and then no one even came back for the chair.
Maybe someone took it out there as an art piece; like a statement on how even the things that helped us sometimes no longer have a place and we should let them go. Because even if we don't they're slowly rusting away.
That's very poetic @themanwithnoname - like your username! :-)