Because git is significantly faster, better at merging, allows cheap private branching and private changes (don't have to do everything in public just to have v

Because git is significantly faster, better at merging, allows cheap private branching and private changes (don't have to do everything in public just to have version control), allows staging of changes, allows offline work, allows "out of band" collaboration between developers, is up to 30x smaller repos (mozilla), more redundant (everyone has full history)... (more)