Why does it have a cult following? Because there are enough people to keep the project going and it makes them happy for whatever reason.
Why does it have far less usage than Vim proper? Because it's a young, niche project, and Vim has been around forever. Same reason CentOS and Ubuntu have a far bigger usage share than any of the "trendy" distros.
Not sure what you are questioning exactly.
Why does it have a cult following? Because there are enough people to keep the project going and it makes them happy for whatever reason.
Why does it have far less usage than Vim proper? Because it's a young, niche project, and Vim has been around forever. Same reason CentOS and Ubuntu have a far bigger usage share than any of the "trendy" distros.