Almost impossible to keep a whatsapp group tidy and organized enough for the needs of an university. It’s hard to properly collect and index useful conversations. Topics get mixed all together. Chat history is local, if you loose your phone you might end up loosing the whole history. You are forced to share your phone number with people you might not even know or trust. You’re handing your metadata to Facebook.

Lemmy would be a pretty cool tool to have, idk, subject-based or course-based communities that allow discussions to develop in comments forests. You can link stuff easily. You have mods moderating these communities which is not possible in whastapp (eg. can’t delete a useless or disturbing post for everyone). People can subscribe only to the topics they care about and are not forced to go through one shared chat history to find discussions they are interested in.

I mean, in general, I find whatsapp groups to be good only for chit-chats. In the messaging world alone (so not considering “news aggregator” sites such as Lemmy) there are far better and friendly alternatives such as Discord, Mattermost, Element, Telegram, which allow a much more organized discussion to happen, with a good degree of moderation and indexing capabilities