Seems plausible
Atlassian software, as least the parts I've seen, was incredibly complex. Probably much more complex than what you'd actually need.
Remember, high complexity means more code, and more code means more bugs, and more bugs mean more security critical bugs.
As for features you need to distinguish between "explicit features" which need to be coded explicitly, and "implicit features" which emerge from already existing features combined in new ways. Ideally you have the later with a small and orthogonal set of explicit features combining into lots of implicit ones with as little code as possible.