The average person doesn't use Xcode, IDEs, or the full Adobe or MS suites. For many a desktop or laptop is used for web browsing, emailing, video, music, games, and other tasks that an iPad is plenty suited for.
Until you actually need to do some real work, like emailing and merging multiple documents to send, or even something beyond super-simple document creation. I tried to live the iPad-only life for a couple years, and it was horrible. Trying to create a spreadsheet or any type of document for that matter is a pain and doesn't offer enough for a user to actually get things done efficiently.
As far as I know, almost all "average people" use MS Office. Literally almost everyone uses it. Especially if you are a student or in business.