These days, much of the world of open source has turned squarely toward using Open Source Content Management Systems (CMS systems) to better manage the needs of today's enterprise and small business.
Why do you have to pay thousands of dollars for something that is offered for Free and it works as well as those expensive systems offered around?
Think about this question….
Can anyone compete with the contributing work of thousands of people?
Whoever this company might be (unless Google or one of the other giants)  it will not have enough  man power and time to develop a good CMS tool and constantly make it better like the  Open Source once.
Using those systems allow us to offer you a reliable product, supported by thousands of programmers , bug proofed and constantly updated to keep pace with modern security and search engine demands.