This is just a bit of expansion on the blog post I wrote 2 years ago on how "WordPress Won The CMS Wars". But we'll picking up on the narrow subject of 2 forks of the original b2/Cafelog script.

As you all know WordPress is a direct descendant of the b2/Cafelog script. But many do not know that the other descendant of b2/Cafelog is the b2Evolution. Unfortunately, at the moment it is languishing as its uptake has never measured up to that of WordPress. But it has been a pretty solid script right form its inception.

b2Evolution has the capability of creating multiple blogs from a single codebase something which WordPress never had until WordPress MU was merged into the main codebase. There are many other features that b2Evolution has had: see its features here and its background here.

So why did it fall behind? In my opinion:

1. Its Name. Yes, the name. Anyone who has read a bit about the Psychology knows the power of brand names. "b2Evolution", while alluding to its origin, is not a good name. "WordPress" on the other hand sounds less generic and more brandable.
2. Its USP (Unique Selling Point). b2Evolution is a Content Management System right out of the box. But a CMS is broad thing. On the other hand, WordPress is NOT a CMS; it is a Blogging Script. By choosing to narrow down on just one samll aspect and doing it really well WordPress won where b2Evolution and other full-blown CMS's failed.
3. Timing. The success of WordPress hinges on the fact that it got its first early adopters at a time when blogging was the hottest trend and was just about to go mainstream. It's this tide that b2Evolution and other CMS's missed.

NOTE: This is not a swipe at b2Evolution. Every CMS developer team has its goals. Sometimes they succeed spectacularly, many become average while majority become failed, abandoned projects. b2Evolution is still available and has moved towards social blogging over time.

Update 18th, June, 2022

Further development of b2Evolution seems to have stopped as from this post. And judging from its founder it seems to have ran into financial difficulties to sustain it.