It enables you to back off, to avoid hand-to-hand fight, and trains your eyes to detect movement. Movements which you can't hear.
11 seconds sound clip from the Crippled Avengers (1978) movie soundboard.
You can hear this line at 00:43:24 in the Blu-ray version of the movie.
Quote context
[...]
- Well now, I did kick him three times yesterday. Now he's more careful.
- Hey, are you really blind, or faking it?
- Hey. Tonight, you practice with me.
- No, no, no. Those iron feet, they hurt.
- Trying to maneuver your learning is useful with an opponent like Tu.
- I prefer being with you. The others, they hit me and kick me.
- Well, now, you've been here for three years.
- We feel whole again, like men. Not cripples. And all thanks to you.
- You're right. Crippling can be remedied. But not mental crippling, though.
[...]