Polyswitches are fairly awful to be used as wire protection devices. The thermal derating curve shows that the 10A rating you'd get at 20C ambient varies to 7A if the ambient temperature was 40C inside an enclosure. If you were to do the silly thing that a lot of people do and jam multiple power supplies into 1 box or run a poorly ventilated box then at 60C the 10A rating drops to 4A. Of a greater concern if the same devices were used in Canada at Xmas time instead of 10A the trip current could be 16A. Also of a big concern is the trip time. An auto fuse will trip at double the rated current in about 0.1s. A 10A polyswitch has a 50A trip time of 6s.
IF a polyswitch were to trip the radiant heat from them would also potentially cause a cascading effect where the heat from 1 would cause adjacent ones to overheat and shutdown.