Not only for disabled users, unless you consider users with RSI or related injuries disabled. The backspace to go back and the space key to scroll are extremely

Not only for disabled users, unless you consider users with RSI or related injuries disabled. The backspace to go back and the space key to scroll are extremely convenient to browse the web with an ergonomic Kinesis Advantage keyboard. They are the biggest keys on the left and right, directly accessible with your thumbs. Removing this behaviour in a browser would make browsing less usable - although it's possible to remap keys on the Kinesis Advantage.