Opt-in privacy is poor because most people don't bother, and this drastically reduces the privacy for those that do. Even if something has perfect privacy featu

Opt-in privacy is poor because most people don't bother, and this drastically reduces the privacy for those that do. Even if something has perfect privacy features, this alone is a deal-breaker. With Zcash you get opt-in privacy, with Monero it's enforced with every transaction, for everyone.