Why did this happen? Imagine it's this data analysts' first year out of school, something like a crappy statistics program that only teaches SAS or base-R with no VCS. This young padawan needs to practice analysis in preparation for a work project. They grab some data and stash it in a folder where Git is tracking. They do their analysis practice, it's Friday afternoon, they get lazy, they don't look at what they're committing, and they click buttons in the GUI without much thought.
It's incompetence and laziness, not malice. These tools that allow us to share widely, not just GH but also social media broadly: these tools have great power that should be used with greater training, responsibility, and care.