Every company?

Vertical integration is an extension of capital’s desire to completely capture any competition into one giant monopoly of possible. Vertical integration allows companies to gain functional monopolies over large parts of an industry usually by buying out the companies that make up the parts.

In this context its the companies that the biggest ones driving development pipelines. Microsoft has become incredibly potent here by buying companies that make up some of the most common development practices for some of the most popular programming languages. As a web dev, Microsoft owns NPM which is where my packages are stored and published, they design the languages I write my software in, in buying Github they own where my code lives and builds as well as their artifacts, they build both editors I use to do the lion share of my work. Then they own the operating system I am mostly commonly accessing these tools from. Because they own all these parts they can make friction between them incredibly low and make every other competing option look frustrating and less polished thus harming adoption and further solidfying their functional monopoly in the absence of it being written out explicitly under just one entity.