It's ALL about the angle.
Yes it is. And every plate presents multiple angles to the shooter. That 20 degree down facing plate has a 70 degree upfacing top edge and every angle between on the top corner. Doesn’t take a very big piece splashing back at 1000 FPS to rip open your carotid artery.
Plus the stand and hanger present odd angles if there is any metal in them, and if the plate isn’t new, it isn’t perfectly flat. And of course most plates have a hole or bolt sticking though with more angles presented.
Think about it. If you shoot steel at 20 yards and their is a bounce/splash back, from the target you are a certain size. At 3 yards you are about 45 times larger (6.66^2), and therefore 45 times more likely to get hit. And at 3 yards even a bounce to the ground and back at you off a small rock can have a dangerous level of energy (more than a very deadly subsonic 22).
3 feet, or 3 yards, just is not safe to shoot steel.
I have shot and RO’d a lot of matches with steel, some of it too close. Not counting the little bits of splashed lead that settle all around, I have been hit incidentally dozens of times, and bled several times. The jackets seem to be the most dangerous but since the lead mostly splashes. One or two hits were bad enough that if they had hit the wrong place it could have been very bad, particularly if I was alone at the range. Steel target shooting should be taken seriously.