Speaking for myself, it’s because future monetization can be easier under mit when using a foss utility and private code.
My project would not exist at all unless there were ways to make money off it.
True, others can also use that same code too, in the exact same way, but that requires quite the investment, and those of us that are doing this are banking on not getting the interest of a monopoly in that way. We are competing against other small businesses who have limited resources.
At the same time the free part can get a boost by the community.
I comment a lot in politics here, and am sometimes an ass, so cannot name this project