So does the real world. Things are hard to do with disabilities. That's what the word means. This has great potential, and it's not worth shutting down because some people aren't able to use it.
I can also see this being very helpful for people who have cerebral palsy, for example. Larger movements are easier, this might help someone use the web more easily.
What if a bank used this for authentication and disable people can't use their custom interface devices? Does that mean that disabled people shouldn't access to their bank accounts?
Maybe if this was the input device that interacts with the standard web, then there is potential here, but it would be unfortunate if a company used this as a primary means of input.
I feel the opposite. The more computer interfacing takes place in software, the better for disabled users. If you have a device that expects a keyboard scancode to respond, then you need to build a physical keyboard to talk to it. Building a physical keyboard that doesn't suck is expensive, and so disabled people pay crazy prices for gear tailored to them.
Tailoring software that can use very general-purpose input equipment is much cheaper. Training a neural net to recognize one-handed gestures, for instance, could be done by one developer then deployed worldwide. Making a decent one-hand keyboard is way less easy and way harder to scale.
I'm fine with using them, as long as alternatives are available for people with disabilities are able to participate as well.
Imagine if your bank started using these to access your account and suddenly disabled customers could no longer use their adaptive input devices to interact with their account.
This is a very valid point, but as a counter argument the technique implemented here could be adapted to help users with other needs like say, a browser extension that can help you navigate back and forward with the blink of an eye.
I can also see this being very helpful for people who have cerebral palsy, for example. Larger movements are easier, this might help someone use the web more easily.