I think that in this case, it's fair to compare the number of people who have a disability instead of the amount of browsing they do, because it speaks to the potential market.
Suppose that there was no technology to help blind people use computers. Then blind people would have 0% of browsing, but they're not 0% of the population -- should we create technology to help them even though they do no browsing? (Yes.)
Suppose that there was no technology to help blind people use computers. Then blind people would have 0% of browsing, but they're not 0% of the population -- should we create technology to help them even though they do no browsing? (Yes.)