I think it might just be because Hexbear is "difficult to understand". If you pick random high score comments from there without context and show it to a data-driven nerd, I doubt they'd even be able to describe what's going on.

But since federation, at some point any (naïve) analysis of either forum will inevitably include a lot of posts from the other. This could be an actually interesting area for social network research (social dynamics between "native" and "foreign" users in an instance), but since there's no ready-made model for this in scikit-learn the Data-Driven bros will never risk actually doing research.