That’s nowhere near true. Alexander the Great, Leonidas, Pyrrhus the Great, Julius Caesar, Subotai, Richard the Lionheart, Hannibal Barca, William Marshal, Admiral Yi, Oda Nobunaga and many more all fought in the front lines at various points or near continuously. And these are the guys called out for being the best commanders of their time, some are in the running for greatest general/admiral in history.
The general up on his hill did develop as the best method when we got modern forms of communication (And even then you got people like Rommel and Roosevelt Jr who occasionally directed right under gunfire). Before that generals went where they were most needed. If their expertise was required to make sure a charge happened at the right place and at the right moment, that’s where they went (if you’re Alexander). Did a section of line need to hold for your plan to work? That’s where you went (Hannibal and Caesar).
Frankly, I think that active style of commander would be an awesome champion. Personally, I think it has potential to be a true AD support, with cool abilities to create options and areas best to fight. That’d be awesome.