Honestly? Because it's become accepted as the industry standard. People who need to make the decision without having knowledge about the topic just go with whatever everybody else is doing. In the past, that used to be whatever IBM was offering, then whatever Microsoft was offering. In that respect, git is a lot better. It's flexible enough to adapt to different kinds of workflows, at least.
Honestly? Because it's become accepted as the industry standard. People who need to make the decision without having knowledge about the topic just go with whatever everybody else is doing. In the past, that used to be whatever IBM was offering, then whatever Microsoft was offering. In that respect, git is a lot better. It's flexible enough to adapt to different kinds of workflows, at least.