Blind people can use the microwave and the computer. The latter usually having special software.
The small little circle I've always seen as not from your sense of sight but your sense of touch. As SS13 only plays on two senses (Sight and Sound) it needs to use them to imitate the other three senses as well (Smell, Taste, Touch). A blind person's screen being completely black would not be able to properly imitate being able to feel their way around as a blind person can, as you do not have the sense of touch. Being able to see that you're 'dragged' in a direction is something you're able to do with your eyes closed, as well as being able to smell the more stuffy air of a maintenance hall compared to the normal halls.
