They're not (Stones aside) we just decided to go into a season with 6 defenders, one of which is 34. Soon as one goes down with injury the strain placed on the others to play every 3 days woth no alternatives was always going to see them all fall.
Dippers have had injuries to TAA, Bradley, konate, Robertson, tsmikas, arsenal have had injuries to white, timber, calafiori, Gabriel. The difference is, they both have the standard 8-9 defenders in a squad so they can cope with injuries and not put too much strain on the fit ones, we do not. It's entirely our own doing and piss poor squad management.