Here are my thoughts.
The article's authors write that algorithmically suggested groups "lead users further into conspiracy land." FB will not change this because profits stem from engagement, and engagement arises from fear and rage. The ad-based business model seeks this exact outcome.
The Fediverse is not built on a model aimed to maximize engagement, and as such is more shielded from the incentive to build algorithms that maximize engagement even if it means going to conspiracy-land.