It is not plausible to suggest zero knowledge proofs are unreliable because "they are younger"
They've been around since the 80s and are well understood.

People have been talking about adding them to bitcoin since forever. I'm not aware of *anyone* who is opposed because they're skeptical of their mathematical properties.

Here Hal discussing them back in the day.
https://cointelegraph.com/news/bitcoin-pioneer-hal-finney-talks-zero-knowledge-proofs-newly-surfaced-video