I thought that was strange too. I use all of those exercises except behind the neck presses, seated presses, preacher curls and behind the neck pulldowns. I don't see any danger in the behind the neck press or the preacher curls….just find them to be generally worthless or have better alternatives. For the leg extensions and curls I'll occassionally use them in weight lifting circuits but they are done with lighter weights in unilateral fashion and probably not used in the means Vern is referring to (as a primary strength builder). I use good mornings, RDLs, and their variants several times a week and haven't noticed any problems.