Comment by layer8

The divergent timeline model is indeed even necessary in the first place to achieve exponential growth. If there is only one timeline, only linear growth is possible (because the subjective history doesn’t split if the timeline doesn’t split, so there’s ever only a single subjective history overall).

Exponential growth furthermore requires that the time jumps are done “atomically” in increasingly larger groups (of people). If each member jumps separately/individually, they would each create their own separate timeline and thus again only add 1 to the member population on that timeline.