The utility wasn't just about remapping keys. It included a suite of quality-of-life features that made it a Swiss Army knife for DotA players.
In the original Warcraft III engine, seeing the health bars of units required holding down the Alt key. This made micro-managing units or last-hitting difficult because holding Alt interfered with other hotkeys. auto warkey dota 1
By default, using items required pressing Numpad 7, 8, 4, 5, 1, and 2. The utility wasn't just about remapping keys