Design is far from the only threat vector. Any implementation that is less than perfect is prone to all kinds of attacks. A few years ago, there was a report that the NSA could decrypt a double-digit percentage of encrypted web traffic thanks to a larger-than-expected bag of factored primes they keep handy.

Great story, are you claiming that NSA can infer from zero-knowledge proofs inputs, maybe map cryptographic hashes to plain input text or something of that nature?

No, but I bet a dollar that NSA isn't just going to collectively fold hands and say "These schemes and implementations are too good and too secure for us to break. We'll ignore the meta data, network analysis, side channels and our data centers that can store 2 days worth of internet traffic; we'll give up and focus on defensive security only"

Your argument applies equally to any initiative ever made by humans that mentions "internet". Yet it appears quite few things exist on the "internet". We do have cryptography with good guarantees available.

My argument is not that those things don't exist - its just that to my knowledge, I never heard of any real-life implementation that's guaranteed to be NSA-proof[1] - you're welcome to offer a counterexample.

1. Your fancy encryption scheme is pointless if your plaintext can be acquired at either endpoints, of if a bug in the implementation leaks data. The security of the whole matters a lot more than the individual parts as attackers go for the weakest link.

You're not transmitting sensitive information in the first place.