The simplest explanation is that the small team of people who ran Future Forum probably just didn't want to deal with Benioff and Salesforce's bullshit anymore. Either that, or they got laid off in one of the recent rounds of cuts.
1. Encryption made WhatsApp inherently more resistant to being polluted by Facebook. They still get access to highly sensitive metadata about contacts and groups, but they can't do the kind of things they did to rape and pillage Instagram.
2. He took his money and his free time, and has invested heavily in supporting Signal. While Meta lets WhatsApp rot and slowly becomes Yahoo, Signal is solidly on its way to become the OpenStreetMap/Internet Archive/Wikipedia of social communication apps.
