When you're trying to aim a parry, the right frame of mind is NOT "this bit of my blade must touch that bit of her blade". The way to aim a parry is "I'll catch that with this".
The difference is one of unity. Thinking of it as a catch, a hit, a ding, or whatever your preference is, unifies the action into something that has a certain shape. That shape may involve two bits of steel approaching and then hitting each other, but this is not essential; what is essential is the general shape of the action.
Kind of like trying to touch your forefingers together with your arms straight. If you just move both fingers and try to aim one at the other, you fumble. If you just execute the action where two hands and fingers join, you just do it.