Sorry, I but I believe you are wrong. Multiple platter drives should not be a problem. The larger drives typically had more than one platter, but I'm not about to take apart any of my larger drives to prove the point.Confused perhaps, but I understood the explanation to mean no dual "platter" drives (1 physical drive comprised of more than 1 physical platter deep inside the guts of the drive, not simply 2 separate drives inside a common case) . If you've ever taken one apart then you know what they're talking about. Multi-platter drives in my experience are generally older technology & likely to be found in the computer tinkerer's junk box.
The explanation specifically meant no multiple drives in one enclosure which was typical of 1TB and larger drives. Now with the newer drives, 1TB can be in one physical drive but the 211s are programmed to not accept any drive out side the upper range of 750GBs.