As an aside, I thought that the Domino’s Pizza v. Guillermo Robles decision was strange. Domino's Pizza stores are local brick-and-mortar operations. They all have telephones and take orders by telephone. That to me would seem to be a "reasonable accomodation" for a vision-impared person who could not use the website to order a pizza.

In the more general sense, a strictly online service that has no alternate means of access probably does have at least some responsibility under the ADA.