Um, again, the Defensive Manuever does full damage AND gives me an AC bonus. This is certainly a tactic I can rely on.
Actually this is the point of the system, you can't rely on it working. It encourages, creative play from Warriors (Fighters are notorious in OSR for being boring.) It allows for "Feat" like "PowersTM" that aren't dependable until you gain some levels, and even then there is a 2 in (whatever die) that it doesn't work. When you're 1st level, a blinding attack is 33% reliable. At higher levels it becomes increasingly more reliable AND more powerful.
Also remember that DCC levels DO NOT translate 1 to 1 with OSR or d20.
Bottom line, the MDoA is DCC RPG's attempt to make the Fighter of old/OSR a viable, interesting & playable character. MDoA is what makes them "special".