So, here's some simple math ...
Chains + soring = ABUSE
Chains + no soring = Training device
Does that make sense? Not every person who uses chains is ABUSING their horses. That is the VERY VERY VERY simple point I am trying to make
Full disclosure: I'm a dressage queen with a saddle seat past (Morgans in MA and ASBs in KY). So I've seen chains being used on non-sored horses. I *know* their purpose and they are not evil unless being used for evil, like soring.
Again, chains + no soring = not abuse! Chains + soring = abuse!