"The hand doesn't move without the center/ the center doesn't move without the hand" ...is a teaching of Daito ryu. One that Howard and I both learned more than two decades ago. It is a specific teaching with specialized exercises solo and paired to learn how to,....activate...hara (dantian). Thus we find it hilarious to read internet personalities and their followers telling us we don't use dantian.
As far as I understand the devil is (as ever) in the details, i.e. what kind of connection is there between the hand and the dantien and what other body connections come into play?
Oh well, small chance we'll ever figure it out without doing a show-and-tell, but just wanted to throw in my 2 cents.