Companies like eQuality Technology service, support, train and develop MediaWiki for customers. The people who use a software are stakeholders in the future success of that software platform.
Because the core software is GPL free software, you could do anything with it including maintaining it yourself. However, it's a large and complex piece of software in an even larger and more complex ecosystem. It's best to "ride on the coat tails" of the WikiMedia Foundation's support of the project. However, there are recent efforts to create a Stakeholders' Group (also at mw:MediaWiki Stakeholders' Group) that would be a united organization to organize and support the interests of third-parties [1] who use the system for different purposes or in different ways than the WMF.
