If your follow up question will be "how can the EU do anything against a company that operates outside of its jurisdiction?", then the answer will be "by making it difficult for people in the EU to do business with Discord".
The EU could restrict payments to Discord for example, cutting their revenue.
Let me answer your question with another question.
Why is it so forbidden to ask this question, and know this answer? It's just a basic fact.
My suspicion is that the GDPR apologists know that it's a weakness for their argument, and are afraid to debate on that.
As it so happens, funnily enough, Discord has a branch located in the EU. This could easily end the discussion of "does the EU have jurisdiction?" The answer is, yes! Discord is a company in the EU!
We shouldn't be afraid of basic facts. If our argument can't survive a simple fact, then our argument doesn't deserve to exist.
If your follow up question will be "how can the EU do anything against a company that operates outside of its jurisdiction?", then the answer will be "by making it difficult for people in the EU to do business with Discord".
The EU could restrict payments to Discord for example, cutting their revenue.