It's a lot like asking almost any other question about how a person with a disability does something people without that disability can do.

What's "wrong" with that question (or most questions like it) is the fact that people aren't educated about assistive technology, or are otherwise incapable of looking it up, so it's a question that gets asked over and over and over, as if blind people are assumed to be living in the stone age or something. Yes, blind people can use computers. We put a remote-controlled car on mars, and nobody blinks. We managed to accurately throw a camera past pluto, and nobody balks. We have successfully taken the physical media necessary to store a gigabyte down from a city block to a chip no bigger than your pinky nail, and there are other chips of the same size with 128x the storage capacity for under 50 bucks, and yet still, somehow, people get so confused and astonished to find that technology is capable of making computers, the internet, phones, and all sorts of other electronics accessible to people who are blind.

That's upsetting because it represents just one of the many ways sighted people tend to "overlook" people with disabilities, not just the blind. People are more than willing to learn about cultures in other countries, but somehow disability culture is still more alien to people than $1

I'm not saying anyone who asks this question is to blame for the vast amounts of ignorance that is required for this question to be a constant mystery to people who are assumed to be sighted and have access to computers. I'm saying it's a symptom of a larger problem, and it's more and more infuriating every time I hear someone ask me "How do you use a computer?"