Both handicap stones and reverse komi have their own advantages, there’s no reason why a reverse komi tournament wouldn’t work. (edit: actually, something might need to be done about mirror go)
So the lack of reverse komi games is mainly because of inertia, handicap stones is the established way of equalizing winning chances (which makes sense historically since komi is a relatively recent invention).
We might see more reverse komi tournaments in the future, there has been at least one organized here on OGS.
[Edit] Here it is:
As benjito mentioned, OGS tournaments doesn’t support it, so it had to be organized “manually”.