The more people who use a browser, the more valuable it becomes. A low price gets more users, more network externalities and more complementary sales. While economists think that tying is seldom a bad deal for consumers, the antitrust courts have made it tough for companies with large market shares to engage in this practice. Unlike the tying of hospital services, the bundling of software is tricky to define. Without passing judgment on the merits of the practice, it is easy to see that surgery and anesthesiologists are two quite distinct products.
Software code is far more complicated.
Just like the words in a book, software code can be organized in various ways to achieve a multitude of effects. Over the course of time, software producers add features to their programs that previously were sold as separate products. Spell checkers, for example, are now a standard component of most word processing packages. Many of these are now integral parts of most operating systems. Microsoft and the government have taken quite opposite views of the right way to think about competition in the software industry.