In Derick Giwner's blog on the DRF, Derick talks about how much devastation the banishment from Yonkers cost Lou Pena as he is now down to about 25 horses from his 100-110 horses. Basically, Pena has to almost start from scratch.
Pena's expulsion didn't just hurt him; how many people did he have to let go of since he lost all those horses? Some may have been picked up by other trainers, some may have been unemployed during this whole period.
I am not saying exclusions should not be done, but some serious thinking needs to be done before you drop the hammer. Not only are you getting rid of the person you want to get rid of, other people suffer with them.