For the same reason they call Duct (Duck) tape Duct (Duck) tape. They started life as such but more uses have been found. Agree about the cheapos though - just look for nylon or a brand name.Don't agree had loads fail just with a small amount of pressure on them. They won't break but the ratchet grip gives way.
In they days when you could only buy only branded ones they were a lot better nowadays mostly cheap Chinese crap.
IMO opinion a totally bodged job, cable ties are cables why else would they call them cable ties.