But once Microsoft had established dominance in the operating system market, it became increasingly hard to take on. There was a powerful network effect: once everybody else was using Windows, and exchanging Word documents and Excel spreadsheets, it became much easier for you to use them too.
Also helped, of course, by the issues WordPerfect had on Windows, which Word didn't have. And the odd compatibility issues that meant that networks couldn't bridge.
Imagine if Standard Oil had merged with Ford, and both used leaded fuel, so Ford cars could only use Standard Oil, and Ford cars ran smoother because of that secret.
