Defend is a rather unique move in that it hacks the main game loop / the narrative economy.
A hold-carrying player has to power to hijack MC moves. They can interrupt soft and hard moves and change them in a kind of ¿firm? move.
On a soft move, by spending holds, the defending players ensure that the threatening attack effectively happens, potentially bypassing other player’s agency and – in a way – transforming a soft move into something harder.
On a hard move, the player spending holds is saying “oh no you don’t, not so fast”, they are allowed to react when they normally can’t. With much less liberty then when faced with a soft move, but nonetheless.
Strategically, if playing to win, spending hold on a soft MC move isn’t optimal. Better to address the soft move with a regular move (or no move at all) and keeping one’s hold for a hard move.
I don’t like the agency-robbing and the strategic parts so much.