Today the new Terms of Service of Stack Exchange have been released, sparking a lot of unrest about its arbitration clause; see the comments and answers on the linked meta above, and also this question.
Does the GDPR prevent Stack Exchange from using the arbitration clause against EU citizens?
In the sense that when there's a massive data leak and a large class-action suit will be filed, can EU citizens do that collectively, as opposed to going through arbitration for each separate user?
The below is no longer applicable, since on the 10th of May electronic opt-out was made available.
Related to this it states that the opt-out currently is a physical letter send to Stack Exchange (how they'd tie that letter to my SO account is a bit vague for me, as I can type any odd user page on my letter, not only my own), but this comment suggests that under GDPR there should be a digital opt-out for digital services. Does that mean that the entire clause is invalid (or however that goes in law), when there is no digital opt-out currently available?