None of those really “feel like” the things they’re replacing. I don’t really even think that should be the goal. They occupy the same space, though, and the infographic would look stupid if it showed all the options in some category, so they just picked a popular proprietary/centralized one, and a popular federated alternative in the same category. In this case discord is a popular chat app, and the most popular federa chat app afaict is matrix.