yes edward they did say that but if applied correctly it works well, i've had no issues using it. And i have tried numerous times trying to 'ease' them out exactly the way kevin suggested even using pb blaster or another comparable penetrating oil only to have it wipe the threads out anyway. The damage it causes alters the torque capability of the threaded area and in just about every case i've done this you just cannot torque the plug properly without it starting to pull out the threads that are left.
Any other tech that may go out afterwards and change plugs will most certainly wind up stripping it the rest of the way out not knowing what had transpired beforehand and inevitably wind up helicoiling it in the end. But hey... if one is uncomfortable using antisieze just put a couple drops of oil on the threads, anything other than dry threads should help.