Supporting users with a variety of capabilities is a given for many different types of software development. Building mobile apps? What version of iOS or Android do you target or test for? What about different device features (GPS, cameras, touchscreens), connection speeds or processor speeds? The set of variables you need to be aware of can be reduced (game developers targeting a console for example) but are unlikely to ever get down to just one scenario.
For web developers, we have all those concerns, but one major constraint is the level of support for various features across the browsers that will be used to visit our site.