I would assume that many companies that does any kind of software development has had some internal tooling developed along to help streamline various aspects of the job. Our biggest such project is definitely our internal development platform.
At some point such tools can grow big enough to warrant their own teams. They need to provide internal support for all the employees using the tools. It also need to be maintained and probably even developed further. When the company grows these requirements for the internal team also grow.
With big enough investment to these tools it might become feasible to start offering those tools to others as well. It could be a lucrative new business extension at best or at least sharing the good will offering it as an open source solution isn't a bad idea. There is always additional value that can be gained from something useful.
But growing isn't always feasible. Especially when money gets involved there is the pressure to keep ahead of the markets to grow the business. It needs to be carefully evaluated whether it's profitable to keep putting internal resources into the tools or looking outside to replace them with something already available from others.