I'm not sure that
randomly connecting nodes is a good model for how software complexity arises, since connections between software components are
not made at random. When was the last time you threw some dice to decide whether some piece of your user interface would be connected to business logic or directly to your database server? There's usually a (non-random) reason for why we add a piece of code, and the reason why complexity gets out of hand is that we don't, for various reasons, refactor our architectures to eliminate accumulated complexity before it's too late (and then nobody can understand it anymore, and you end up with the ball of mud).
It's also interesting to note that Foote and Yoder's "Big Ball of Mud" paper[1] portrayed the mechanisms for mud-ball formation as a set of anti-patterns. It's an interesting read. Their give some pretty thoughtful explanations for how software transmogrifies into a mud-ball, none of which include random processes.
[1] http://laputan.org/mud (1999)