Bear in mind that lots of Citron’s early shorts were basically discovering cases of straight up fraud. They expended resources to research that fraud which ultimately made markets more efficient as this information was shared. So the argument that they can help with price discovery is compelling.
It’s hard to picture what a world of purely long-only funds would look like, but it feels like it would be quite problematic. Maybe shorts bring more problems than they solve, but they do still bring advantages.