Org mode has a long tail of features. -- So org mode has a similar problem to how vi-emulation in other programs will often miss out on some niche behaviour.
Using org mode as an outliner is likely to be easy in a variety of tools.
A major part of org mode is task management, integrated with an agenda view. The full set of editor interactions would be harder to implement in other editors.
e.g. One feature org mode has is "org babel", which allows running snippets of code, and gluing these together as a way of doing literate programming.
Or e.g. the tables in org mode support spreadsheet calculations.
-- I'd say more that people find many different uses for org mode. That somewhat speaks in favour of org mode as a tool.