For instance, Microsoft Office is the de facto standard in business. If you’re sending business files to others, they’ll probably want Microsoft files. There are other office packages, and Microsoft programs can open their files. But that requires thinking. Most people don’t want to be bothered.
Microsoft Office is generally the standard at colleges, too. Students can work in labs. But labs are crowded, and sometimes lines are long. So, students prefer to use their own computers. Those files have to be exchanged with other students. That’s most easily done with Microsoft Office.
Again, files from other programs will usually work. And students are likely to be more flexible about opening them. However, if an important file won’t open, angry words could be exchanged.