It would be a forum security feature not so much a user security feature. The plugin keeps a record of a bunch of user datapoints so you can identify sock puppet accounts. I’ve seen people make alt accounts on discord to trick others into trusting them and then scam them, so with vigilant admins and mods it could be a user security feature 
But I do agree in europe without modifications to the plugin this wouldnt be legal.
Discourse Fingerprint - Browser Fingerprinting Plugin - Plugin - Discourse Meta