It's interesting that you are mainly considering the experience of a hypothetical small business owner and what they would be happy to do, and not the experiences of disabled people, and what's easy for them.

It's a lot easier to fix the issues the Justice Department mentions, and it's really a pretty short list, than it is to live with a disability. If your business is open to the public then it has certain responsibilities under the law.

Anyway phone calls don't necessarily work well for deaf blind folks, people with disorders like ALS (Stephen Hawking etc), and some folks on the autism spectrum.