Like lavabit or anon-penet.fi, cases where things go tits up for non-provider related reasons.
I actually agree, and personally I don't love how they advertise such foolproof security. It's dangerous especially when their non technical users don't understand the consequences. I've had multiple friends using Proton who think it's 100% private even when emailing a gmail user.
I recalled this when I read some crypto security efforts were focused on removing any javascript dependencies. I was like... hmmmm.....