traditions proliferate because of network effects and cultural momentum
Yes, that's the mechanism of their transmission. But their PURPOSE is to reaffirm cultural norms, chiefly ones related to humility and basic conformity to one's society. Not the "I'm going to do literally everything exactly the same as everyone else" sort of conformity, mind you. Just the BASIC kind of conformity and humility. The kind that says "I'm no more valuable than everyone else in the community."
Rushing to join a new tradition (especially one that hyper-celebrates one's own reproduction) is an indication of the opposite impulse. You're communicating that you're better, more important, more valuable than your peers and your ancestors. That's destructive and maladaptive. Not everyone can be the best. If everyone thinks they're the most special, then nobody will want to do the equitable sharing and sacrificing that all societies have to do, in order to keep running.