You'd think disabled people who cant get out much would have investigated the net years ago.
It's almost as if they were suffering from an impairment to their ability to do stuff - and that this was holding them back somehow...
For example, braille is harder to use than text. It's slower to produce, slower to read, physically harder to do and takes up loads of space. My Mum is qualified as a VI teacher in her 40s - and has taught braille ever since. But she was never able to read it by feel - not a problem as she just looks. But many people who go blind later in life, also can't - and end up having to learn moon. Which uses bigger shapes - and thus takes up even more space. A blind kid I know did Lord of The Rings in English at school. It's a 13 volume book, each volume being 2' square and an inch thick.
Speech and listening area also slower than typing and reading text. And create problems if you try to do them in noisy environments.
Though you can now get a brilliant screenless laptop called a Braillenote (other brands may be available) which has either a 20 or 40 character braille display done with moving pins. But they are quite hard to use.
A few years ago, a company created a satnav. Entirely voice interface. But the layers of menus required to get most sat navs to work how you want, meant that only the brightest blind people with the best memories could operate it. Nested menus are so much easier to navigate when you can see them / and don't have to hold the menu structure in your head. So what you can now get is a sat nav where it tells you where you are. Thus if you get on the right bus / train, you know where to get off. It is either programmed for a specific destination from your home PC, or you can press the save this location button - so you can navigate your way back somewhere.
If you're deaf/blind then of course voice interfaces are bugger-all good to you.
If you suffer from certain physical disabilities, then you're only going to get on the net voice-activated if you've got someone else to physically set up the system for you.
Plus, as a general rule, some people are better at problem-solving than others. And that difference applies to disabled people as much as anyone else. They just have more problems they need to solve, and often less money/help to be able to solve them with.